Dual Battery monitor on Proffieboard v1.5

Dan-Tron · June 17, 2023, 11:44pm

My friend and I bought a couple Proffieboard v1.5 's quite some time back and only now are finally using them. So far it’s going well except I wanted to know if it is possible to use an external voltage divider circuit connected to a spare Data pin to monitor the battery capacity. We are using two 26500 batteries in series with a DC-DC converter (BRNS20 Cosel) to deliver a constant 3.7V to BATT+. We are using Data1/ID for the WS2811 blade and Data4 for WS2811 crystal. Data 2, 3, 5 are free. Do any of these support analog in for measuring battery voltage via external divider?
Thanks!

profezzorn · June 18, 2023, 3:10am

The answer can be found in this file:

github.com

profezzorn/arduino-proffieboard/blob/6c36f58ef94e791734bcb69d8f20b40c40141ab6/variants/STM32L433CC-Proffieboard/variant.cpp

/*
 * Copyright (c) 2016 Thomas Roell.  All rights reserved.
 * Copyright (c) 2016 Fredrik Hubinette.  All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal with the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 *  1. Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimers.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimers in the
 *     documentation and/or other materials provided with the distribution.
 *  3. Neither the name of Thomas Roell, nor the names of its contributors
 *     may be used to endorse or promote products derived from this Software
 *     without specific prior written permission.
 *

This file has been truncated. show original

Searching for PIN_ATTR_ADC, we see that the following pins can work with analogRead(): 14, 16, 17, 18, 19.

14 is vtest, already used for battery monitoring
16 is data1, which could be used for this
17 is data4, which could be used for this
18 is LED2, but connected to the FET, not the pad
19 is LED3, also connected to the FET, not the pad

So, none of the pads you currently have free are analogRead-capable. However, you can move the data1 and/or data4 wires to another pin to make it work. You’ll also need to make some code changes of course, but I can help with that if you need it.

Dan-Tron · June 20, 2023, 6:14am

Thanks! We moved the crystal from Data4 to Data2 successfully which freed up Data4 to be used for an external voltage divider. We’re still ironing out the custom code for that but so far it is looking promising as we have a working battery level, it just needs some fine tuning to be more accurate.