| A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | |
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1 | # | Requirement | Why ? | Discord Username | Comments | Must_have | Nice_tohave | |||||||||||||||||||
2 | 1 | Support ESP32 S2 modules | The ESP32-S2 is targetting power efficiency and has an ULP programmable in C not assembler. An Arduino core branch is also in preparation. Although this is important, I think that it is not a main factor as it is not much influencing the design. Altough it is to check if the efficiency would not rival an external RTC so require less external components. | wassfila | X | |||||||||||||||||||||
3 | 2 | power cut-off circuit + RTC Timer | Cutting off the power lowers the current draw to <1mA | Informatic0re | (tealbrains) include SRAM if cutting power to ESP32 in order to store variables | |||||||||||||||||||||
4 | 3 | Actionable documentation | Containing: principles & block diagram, wiring diagram, BOM w all components and mechanical parts / connectors, Normal operations levels (can be notes on cct diagram), troubleshooting flow.... | LEMD49 | X | |||||||||||||||||||||
5 | 4 | 3v3 Output | Power supply for ESP and sensors | X | ||||||||||||||||||||||
6 | 5 | 5V Output | Usefull for sensors which need 5V but should have a on/off | (tealbrains) Use a boost converter with Enable pin to save power, when not needed, turn off. | X | |||||||||||||||||||||
7 | 6 | USB charging | X | |||||||||||||||||||||||
8 | 7 | Solar charging | Power for the system when it is installed in locations where USB is not available and where swapping the battery every year or so is not desired | (tealbrains) this requirement will likely fulfil requirement 6. perhaps a usb connector + screw terminals? Must think about combining both inputs if both are implemented. What type of panels/voltage range should be supported? | X | |||||||||||||||||||||
9 | 8 | Charging while powering | (tealbrains) make sure the device does not end in a loop of death if the source has insufficient current | X | ||||||||||||||||||||||
10 | 9 | Replacable batteries | X | |||||||||||||||||||||||
11 | 10 | Fuelgauge | we need a feature to measure battery health. | |||||||||||||||||||||||
12 | 11 | Low voltage signal/alarm/interrupt | (wassfila) If the voltage can be connected to the ESP, the ULP could run the ADC and wake up the main ESP core when it detects low voltage. | |||||||||||||||||||||||
13 | 12 | Battery low voltage protection | X | |||||||||||||||||||||||
14 | 13 | Over charge and discharge protection | X | |||||||||||||||||||||||
15 | 14 | charge indicator | (wassfila) Just an idea, what if the ESP participates in showing the charge with leds or even RGB led. Only while charging or after a button press but not permanently to avoid discharge. | |||||||||||||||||||||||
16 | 15 | Maximum Battery life (sensor mode current 20 ~ 30uA, life 1 year) | Define the maximum achievable savings by the modular design, (e.g. short wake up, send ESP-NOW packet and back to sleep). | wassfila | I agree that this is a SW topic, the idea is to link the HW design to an applicative goal. I'd like to know what is the achievable limit and maybe have it as requirement. It is possible to define this as deep sleep only without counting number of wake up cycles, but he consumption of wakeup cycles should also be reasonable in comparision not 1% from sleep current and not 99%. | X | ||||||||||||||||||||
17 | 16 | Minimum Battery life (e.g. performance mode current <200uA, life 3 Months) | Set a target for the least achievable performance of the modular design, e.g. when deprived from all external optional components. e.g. no external RTC. | wassfila | This mode might open possibilities of using esp-cam as a low power time-lapse for example, so link to hardware is to think of modules connectivity. A modular design might cover both 15,16, but I just wanted to limit both extrems of where we want to push the performance. | X | ||||||||||||||||||||
18 | 17 | Specify a maximum quiescent current | (Instead of 15. and 16.) Lifespan of device will be application dependent. The property of this circuit must be independent. For example, fix quiescent current to be < 50uA. | tealbrains | Perhaps a vote to set this value is required. | X | ||||||||||||||||||||
19 | 18 | ESD security | Every electronic device requires CE conformity, CE conformity includes Emission, G-Tem, ESD, HF, Burst measurements You should follow these guidelines even without CE conformity | RV3Dtech | X | |||||||||||||||||||||
20 | 19 | I2C Interface & Arduino Library | quick acceptance, easy integration for beginners | RV3Dtech | tealbrains(neutral), it's a great thing to have (if it has power monitoring etc). In my experience these charging chips are more expensive and might not do solar. | X | ||||||||||||||||||||
21 | 20 | Security of supply of the components + 5y | the procurement market is changing rapidly, security of supply over a long period of time saves trouble | RV3Dtech | X | |||||||||||||||||||||
22 | 21 | Breadboard friendy design | you know why | Informaticore | X | |||||||||||||||||||||
23 | 22 | Multi-chemistry | Some users may use Li-Ion, others may use LiFePO4. NiMH is broadly available | tealbrains | Open for discussion, they both have their advantages | X | ||||||||||||||||||||
24 | 23 | Temperature (over and under) protection | Safety (can't charge battery at any temperature, there is a risk of damage), can be part of the charger IC | Thomas (added by tealbrains) Comments by david82 | 110f/45c is a top level limit for polymer charging, you should not continue charging a lithium battery at that temperature You also shouldn't charge below 0c/32f | X | ||||||||||||||||||||
25 | 24 | Battery heater | If used in cold areas there might be many weeks/months of continious battery temp too low for charging. | Thomas | Divert solar power to heat battery to above 0c/32f so charging can start. | X | ||||||||||||||||||||
26 | 25 | Charger control (enable/disable) | Reduce the number of charging cycles (specially for solar applications, where we may not want to charge the battery constantly) in order to increase lifespan of battery. AND allow to measure the battery voltage accurately | tealbrains | enabled by default | X | ||||||||||||||||||||
27 | 26 | Support Li-Ion Chemistry | Some users may use Li-Ion | tealbrains | split of 22 | |||||||||||||||||||||
28 | 27 | Support LiFePO4 Chemistry | Some users may use LiFePO4. The chemisty is better for cold climates. | tealbrains | split of 22 | |||||||||||||||||||||
29 | 28 | Hysterisis between battery low and battery ready. | Solar devices in winter may bump along at minimum voltage for extended periods. For some applications, it may be better for the micro to go to sleep for an extended period to allow the battery to charge more than the minimum amount. | metimmee | Offer the option for solar powered devices to remain dormant until the battery is more recovered than just the minimum voltage. When the battery is recovered, produce a wake up signal to kick the micro into life. | X | ||||||||||||||||||||
30 | 29 | Optional OLED based small info display | can display self health and other parameters without being attached to target system | Wajid | X | |||||||||||||||||||||
31 | 30 | cascading option for increased power | for example some project need more power then it can simply stack the power supplies to increase power | Wajid | X | |||||||||||||||||||||
32 | 31 | Designing a full featured (one or more) board and a standalone board for "any" application with the same requirements. | It allows to have a ready to go board. Or to have a module. | Vincent (inspired from Discord - I do not remember the name of the author...) | ||||||||||||||||||||||
33 | 32 | Modular architecture with optional components | Although this might be the main idea already, I added it as requirement to refer to it and translate its impact on the design. This might have to be broken down into what is modular and what not ? RTC optioanl, ESP32 itself optional as mentionned in req_31 ? ... | wassfila | ||||||||||||||||||||||
34 | 33 | Test Points | We need test points at any usefull position for proper validating of the circuit | Informatic0re | X | |||||||||||||||||||||
35 | 34 | Expose ESP32 Serial pinouts for flashing | If we plan to have a module soldered on the PCB, we would need to flash it, a serial to usb converter might not be necessary to be on the pcb as it could be similar to the ESP32-cam with external serial to usb. | wassfila | This raises questions about expectations from the modular architecture, how finalised the design should be, ready for production or hobbyist friendly by exposing pre-development pins such as serial and maybe more. | X | ||||||||||||||||||||
36 | 35 | LOW power consumption (of the regulator board itself) | In Solar powered applications, the overhead power consumtion of chargers/regulators can be too much. | Some people want "status LEDS" etc to see status of charing and battery level, etc. In my opinion good for prototyping but "too energy expensive" in real installations where we need uA to be consumed and cananot allow mA. This is for me an important requirement. As an "requirement option" it could be possible to have a mechanical switch to disable any such overhead. | X | |||||||||||||||||||||
37 | 36 | Wemos D1 mini shield | It is nice to have the power board directly fit on the Wemos D1 mini as many other shields | X | ||||||||||||||||||||||
38 | 37 | Usb C | This will make it more future-proof and its going to be nice to have the new usb standard while not having to worry about wich way you connect the usb | fabrifer020 | Its open to discussion because I think it would be nice to have it but I also think we all have more usb microB or miniB than we do usbC cables | X | ||||||||||||||||||||
39 | 38 | Reverse voltage protection | To not fry our Boards with a common mistake that could be prevented with just a few components and negligible current loss for saving our boards | fabrifer020 | X | |||||||||||||||||||||
40 | 39 | Adjustable output voltage (buck/boost) | To allow the board to be used for multiple projects which may have varying power requirements | davidfet | Is there a benefit to having both a 5v and 3.3v vs. variable? Remove this requirement if deemed out of scope... | |||||||||||||||||||||
41 | 40 | Controllable 3v3 Output | A 3.3V Output which can be tunred on and off by the MCU to power sensors and other things | leven | X | |||||||||||||||||||||
42 | 41 | Create (1+) standard slots for expansions | Some features are "nice to have" such as additional buck / boosts, or power bus controls. Ultra-low power modes such as using an RTC + SRAM. These features are not "core features" so leaving the slots unpopulated by default will allow the team to develop some expansions and the users to also develop their own expansions if they need to. | tealbrains | X | |||||||||||||||||||||
43 | 42 | Define maximum/minimum acceptable size | This will limit the number of options, connectors, etc and requirements that can be met. Is having a connector for 18650 for example a good idea? Or 14500? etc | tealbrains | More than a specific requirement it's a global requirement that will limit the other features and requirements | X | ||||||||||||||||||||
44 | 43 | Expose Battery pins (post protection) | This allows the user to power some modems or loads directly from the battery without extra losses that occur using a voltage regulator | tealbrains | X | |||||||||||||||||||||
45 | 44 | Power on-off behaviour, similar to a mobile phone | Possibility to power off via a button and via a MCU signal. If external power transitions from off to on while the board is powered off because of low battery, then power it on. But do not power it on if battery level is OK, indicating powering off was intentional (via power off button or MCU signal). This behaviour would be helpful when the external power is intermittent (solar pannels, mobile units similar to a phone). It would allow automatic restarts when external power is available after a powerdown because of low battery, while allowing for voluntary shutdown too. | Florian | [Florian] I haven't seen an external "switches" that would behave this way -- but then, I'm pretty ineperienced. I've tried to implement such a behavior using the following circuit as a switch, and a derivative-pulse + comparator for ensuring the power-on when the external power came back. Not sure if that's a good solution though. http://www.mosaic-industries.com/embedded-systems/microcontroller-projects/electronic-circuits/push-button-switch-turn-on/switching-battery-power | X | ||||||||||||||||||||
46 | 45 | Support For ESP 32 Modules | Support for different Modules like ESP32-Wrover, ESP32-Mini, ESP32-Wroom etc And providing breakouts for those also | Trance_Paradox | X | |||||||||||||||||||||
47 | 46 | Having Both Holder And Connecter | Having both 18650 Holder and connector terminals for li-po battery would provide grea flexibility | Trance_Paradox | [Noki] Having only connector terminals would reduce the dimensions of the board and allow to use different types of batteries with differen holders. I would love to see at least throug holes where you could place your own connector. | X | ||||||||||||||||||||
48 | 47 | Toggle switch to turn on and off boost circuitry | boost circuit takes considerable amount of stand by current (quicient Current). if the user have the option to turn off the boost circuitry by a toggle switch(or simply by a jumper) and use only the 3.3 V from a ldo would be beneficial when working with 3.3 V low power devices. | x | ||||||||||||||||||||||
49 | 48 | option to turn on and off boost circuitry by the mcu. | when working with a 3.3 V mcu, some parts of the device (some sensors) may require 5 V. when mcu wakes up from the deep sleep, mcu can turn on the boost circuit to power the external modules that requires 5 V. Then before go to sleep, mcu can turn off the 5V boost circuitry to save more power. (boost circuit take considerable amount of stand by current). This can be easily done by the enable pin of the boost ic. | if we choose the right ldo to make 3.3V, it doesn't take much quicient current. But even a good boost circuit takes 300 uA of stand by current | x | |||||||||||||||||||||
50 | 49 | consider modularity; e.g. having additional boost / display options as hats | to keep base price / complex of basic supply as low as possible. the hats need not physically sit on top of each other or require additional board space but could be connected via 2.54mm dupont pins to keep the basic board as compact as possible | johnheuk | ||||||||||||||||||||||
51 | 50 | must have short circuit protection on the output | we all know why...... :D | johnheuk | X | |||||||||||||||||||||
52 | 51 | at least the outputs should have 2.54mm jumper pins for quick connection to a breadboard, ideally there should pins and pads for the input, battery and output | pushing modules into a breadboard can be difficult / the user may not have one to hand / they use up a lot of space. for permanent installation, solder pads would be a good idea. this would also allow the user to monitor incoming / storage & outgoing voltages more easily. some people may want to tap into the battery supply itself as batteries typically offer much, much better noise performance | johnheuk | ||||||||||||||||||||||
53 | 52 | ideally there should be two or three such 2.54mm pins for the output and they should be positioned on opposite sides of the board, not adjacent to one another | the user may want to connect one set to their micro and another to a different module. i have managed to exploderise a breadboard power supply 30 seconds after powering it up after i accidentally shorted the gnd and vcc output header pins checking the voltages with a meter probe - the pins where right next to each other | johnheuk | ||||||||||||||||||||||
54 | 53 | consider adding a barrel jack / screw terminals to at least the input and possibly screw terminals to the output | not everyone has a soldering iron, or one that's good enough to solder to via stitched ground planes, or may not have a spare usb lead. having a few different connection methods would be great | johnheuk | ||||||||||||||||||||||
55 | 54 | MPPT (power tracking) / scavange / harvest | if the device is trickle charging from a tiny solar cell, having an MPPT type charge controller may be a good idea. could also look into other harvesting methods, e.g. RF, although the power available is likely to be even lower (we can assume that many of these devices will be in range of a standard WiFi router though). | johnheuk | ||||||||||||||||||||||
56 | 55 | strain relief built into the board; e.g. holes drilled near connection points that the user can loop the wire through and perhaps add some epoxy glue to (not that epoxy really needs to be kept away from copper as it is acid catalysed and can begin to corrode exposed copper | if a squirrel attacks a node the wiring will be less likely to be ripped from the board; fewer pads lifted etc | johnheuk | ||||||||||||||||||||||
57 | 56 | a hat option to measure Joules of energy consumed; this could be applied to both the esp and pi but would be particularly well suited to the pi | a feature of Texas Instruments' Code Composer is that it will suggest alterations to code; e.g. use a timer instead of a loop. their MSP430 demo boards go further and can actually monitor real world energy usage when running code, so the user can tune their code and get a better idea of how long the supply will last. this is a feature entirely missing from the esp hat would as far as I'm aware but could be very useful for checking deep sleep type operations. we need to start thinking in terms of Joules per operation / byte sent as opposed to mA | johnheuk | ||||||||||||||||||||||
58 | 57 | echoing other requirements, a rtc seems with a wake up trigger seems to be a fairly fundamental requirement for really deep sleep | being able to shut down the boost / linear regular can create significant power savings. numerous regulators can supply a 'power good' flag. an rtc is useful not only for really deep sleep states but also telling the time - esp boards typically do not feature an rtc; perhaps this could be made available as a plug in type hat | johnheuk | ||||||||||||||||||||||
59 | 58 | try to keep 'taller' components together, next to each other or inline with each other; e.g. screw terminals inline with the battery | this will help squeeze it into smaller spaces | johnheuk | ||||||||||||||||||||||
60 | 59 | try to avoid placing any components along the edge of the boards | many people may find it easiest to mount the boards by sliding them into a 3d printed enclosure feature a slot in the walls; this won't be easy or necessarily even possible if there is a component on the edge of the board | johneuk | ||||||||||||||||||||||
61 | 60 | add a warning regarding enclosing the supply in confined / none ventilate 3d printed enclosures and possibly including a stick on heatsink for any switching elements | even though a target usage is deep sleep applications, many may want to use the module for higher power prototyping work or have the esp running continually. numerous people have burnt out power supply modules by enclosing them in compant, none ventilated 3d printed enclosures; consider offering stls specifically for mounting them (both ventilated and not); consider adding strain relief via 3d printed enclosure. if trim pots are used for a hat, these could potentially be accessed via 3d printed dials on the enclosure itself; add reminder not to adjust trim pots with metallic objects | johnheuk | ||||||||||||||||||||||
62 | 61 | tracking solar panel; additional add on module | if solar is being used, an additional 'hat' option could be to have the panel track. given the low power usage requirement, it would likely be better if this was achieved through a system that didn't include RV servos or steppers being continually engaged. this could possibly be achieved via a 3d printed high gear ratio (so the panel doesn't move in the breeze even with the power removed) or some form of solenoid like lock on the panel tilt that is normally engaged; so it only energises to move. it may not need to continually track, just point in roughly the right direction at the right time of day (e.g. east in the morning, half way in between at lunch time, west in the evening) to reduce movement frequency. this could be also be achieved by rotating some form of cam or actuating some form of ratchet. this could be particularly useful for higher power applications; like the pi, or more continuous wifi usage via the esp. it should use readily available, generic motion components as opposed to end of line / stock clearance microsteppers | johnheuk | ||||||||||||||||||||||
63 | 62 | Smallest Board config size 4cm x 3cm | I input this as initial starting point as stated in the video in time 12:50. It is only to give a guideline for the moment not to deviate too much but given all other requirements this might have to be reconsidered in case some features are really attractive. | wassfila | ||||||||||||||||||||||
64 | 63 | Expose unused ESP32 GPIO Pins | The reference board in the video shows gpio exposed on a header on the sides, and it makes sense that a maker that needs this PCB also wants to use the ESP32 gpios he paid for. | wassfila | ||||||||||||||||||||||
65 | 64 | minimal config costs less than 10 € | Given the market where charging modules cost 1 ~ 2€, and ESP boards 5 ~ 8 € including lcd screens : 10 € sounds attractive. Let us place ourself in the buyers side, and think what we would pay for it ? Let's say this board is special and would be made on demand so maybe 15 €, but if it is 20€ or 30 € would you buy it ? | wassfila | ||||||||||||||||||||||
66 | 65 | 3d printed case | If this is agreed, it could relax constraints on fitting PCB holes to existing housing standard format as discussed in discord. This could give more flexibility and is today a reasonable expectation from every maker or every one that has a maker as a friend. | wassfila | ||||||||||||||||||||||
67 | 66 | Optional Battery format 16340 (16 mm x 34 mm) | This is mentioned by Andreas in the video time 12:50 and because 18650 is much bigger than an ESP32 module and 16340 fits quite good and matches the size req 62 | wassfila | ||||||||||||||||||||||
68 | 67 | Operating Temperature range -20° 70° | The ESP32 operating range is -40° 125°, but the batteries have more restricted range, so we might save on other compoenents as we don't need the full range. | wassfila | ||||||||||||||||||||||
69 | 68 | Charging Temperature range 0° 45° | Charging between 0°-5° might be possible but below 0° might damage the battery. I tool Li-Ion as reference. These could be configurable if it is LifePo. | wassfila | ||||||||||||||||||||||
70 | 69 | The design has to be Open source | As stated in the video timing 14:15, I take these requirements here so that they're visible to everyone even to those who do not remember every word of the video. | wassfila | ||||||||||||||||||||||
71 | 70 | It can be manufactured by JLCPCB | same, from the video 14:15 | wassfila | ||||||||||||||||||||||
72 | 71 | Parts should be availabe from LCSC | same, from the video 14:15 | wassfila | ||||||||||||||||||||||
73 | 72 | battery ampere meter | This would allow used capacity calculation and is different than overcurrent protection. Also stated in the video 15:52 as one reference board had this function, so even if it is hardly feasible, it is worth putting this on the table. | wassfila | ||||||||||||||||||||||
74 | 73 | Optional flat battery pack connector | allows an even more compact size than the 16340 so gives more flexibility | Informatic0re | ||||||||||||||||||||||
75 | 74 | Allow to use super capacitors instead of batteries | Sensors that don't require frequent updates could easily be powered from supercaps instead of batteries. Even frequent measurements are not a problem if you store them and only transmit multiple collected measurements together from time to time. Supercaps are easy to charge, are not subject to overcharge and have a good low-temperature charge and discharge performance which makes them great for outdoor usage in cold environements. Supercapacitors don't require a battery heater, but might require a larger panel to compensate for the higher self discharge. | Noki | ||||||||||||||||||||||
76 | 75 | Parts can be hand soldered | for user who opt not to use a specific function in the board can choose not to solder the parts and to reduce the board's cost. BGA is a no no | himynameisbuzz | ||||||||||||||||||||||
77 | 76 | Add PTC Resetable Fuse in design | Preserve other components due mistakes in assembly and operations, increase reliability of new design | veilands | ||||||||||||||||||||||
78 | 77 | Inclusion of LORA Option | Provision of a low power option for a LORA board such as an RFM95 or the like. | mtroyer | ||||||||||||||||||||||
79 | 78 | USB-C Power Delivery | Faster charging, future-proof | sto | Definitely just a nice to have, as it might be complicated and/or costly // addition by fabrifer020:USB C PD will add far more complexity that's absolutely not needed for the proytect and the charging current is actually controlled by the lipo charger and not by the input current so there is no point for USB C power delivery in this proyect. And USB C PD is really expensive nowadays. (specially good chargers) | x | ||||||||||||||||||||
80 | 79 | Battery connector and USB port should be on different sides of the board | It will make it a lot easier to design a case. The Wemos D1 battery shield has both ports on the same side, and it is a problem. | sto | x | |||||||||||||||||||||
81 | 80 | Provide variants for multiple boards | ESP8266: ESP-12F, ESP-WROOM-02 | ESP32: ESP-32S, ESP-WROOM-32 (etc) | sto | This might not be easy but is worth looking into, in my opinion | x | ||||||||||||||||||||
82 | 81 | USB-to-serial interface, powered only on the USB port | A single USB port used for both charging and flashing is more convenient. It would also be more efficient to prevent the USB to serial interface to be powered on the same power rail as the ESP, as we'd prefer to avoid wasting energy on it when it's not plugged to USB. | sto | x | |||||||||||||||||||||
83 | 82 | EN pin is pulled up through a jumper | Most dev boards hard-wire the EN pin pull-up. It would be convenient if I could deconnect it without having to unsolder a pin, a resistor, or cut a track. Then I could connect it to a GPIO, or a latching circuit, and allow the ESP to turn itself off. | sto | Jumpers take a lot of space on a board, maybe there's an alternative? | x | ||||||||||||||||||||
84 | 83 | USB pass through charging | This will allow the board to be plugged into the mains and charge the battery and still supply power to the MCU. Automatic fail over to battery power when the mains power goes down is also expected. | v-c | X | |||||||||||||||||||||
85 | 84 | One on board multi colored LED connected to the GPIO pin. | This will make the board also usable to notify users via color of the RGB LED. | v-c | x | |||||||||||||||||||||
86 | 85 | sd card interface with power cutoff | for storing data locally and cutoff to save power due to high quiecent current of sd cards sometimes | tobi | x | |||||||||||||||||||||
87 | 86 | Over Voltage Protection for LiPo / Li-ion Batteries | Lithium ION Batteries can ignite ("make Fire") if an an over voltage occurs during the charging process. That's a battery safety requirement | ManWithNoName | X | |||||||||||||||||||||
88 | 87 | Wireless charging | It is mandatory for waterproof devices that have to be charged while operates in precense of water jets or immersion. (IPx3 - IPx7 raiting) | e_sttban | It would be great if it is a module before the charger. | x | ||||||||||||||||||||
89 | 88 | Open Hardware License | We might need to choose a license to open source our hardware properly | Noki | ||||||||||||||||||||||
90 | 89 | Form Factor | Define PCB physical constraints in order not to consume too much space | Antologija | Probably should not be bigger than the NODEMCU board, it would be nice to make it stackable | x | ||||||||||||||||||||
91 | 90 | Having the ability to choose how much current output we get (this will further expand the capabilities of the board and its scope of projects) | Because we all have different current needs and to keep the ability of the board to draw as little as possible while also being able to provide a decent amount of power I was thinking: -In the 3.3v lets just leave only one ldo (or the minimum required) so that it can draw as little as possible but also leave some more ldo's in parallel connected with 0ohm resistors paths that would be soldered by hand if more current is needed 3 to 4 would be the ideal number giving us a good range of current we can get in the 3.3v rail. Of course the number of ldos we have depends in which ldos we are using because we could use one that's really low output current (the one that's always connected) and two more that consume more but have quite more output current. | fabrifer020 | solder jumpers work fine as well and any other way of connecting them, further explanation is in the link | X | ||||||||||||||||||||
92 | 91 | Load sharing | Load should be powered only by charger if available and so bypass battery usage when possible to prevent unneccesary battery cycling | RickTizz | requires stable charger\input power | x | ||||||||||||||||||||
93 | 92 | Overvoltage protection on 5V/USB output | To ensure that a connected device is not damaged by a fault or spike on the board | colsenfoto | ||||||||||||||||||||||
94 | 93 | Conform to JEITA charging temperature standard | Li-ion batteries should not be charged at full current over 45C and not charged at all over 55C. It will lower their lifetime and possible make them dangerous | colsenfoto | A lot of charger-devices have build in JEITA support and only needs an NTSC | |||||||||||||||||||||
95 | 94 | Minimize EMC and noise on switching-output | If used for analog sensors or other analog circuitry, switching noise can significantly lower the accuracy. | colsenfoto | Use snubber circuit on switching nodes and capacitor+inductor+ferrite-bead on switching output | |||||||||||||||||||||
96 | 95 | Power Supply of 1000 mA | The ESP32 datasheet recommends a power supply with an output current of 500 mA or more. Although in practice RF usage is around 250 mA. If we leave more room for sensors, we should land between 600 mA minimum and 1 A recommended for safe usage without heating up much. | wassfila | ||||||||||||||||||||||
97 | 96 | holes added near the 4 corners of the PCB, to be used for mounting PCB board to a platform / 3D printed enclosure | for easy mounting | rob | hole sizes shold be large enough for a small screw/bolt; the centre of the hole should be spaced at an easy to work with measurement, for example exactly 20.00 mm or 20.25 mm, but not 20.167 mm; assuming a retangular board, there should by symetry between the space between the holes - for example the two on one end of the board should be spaced in the same way as the two on the other end of the board and be an equal distance apart | x | ||||||||||||||||||||
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100 |