Posts made by Kabron

It works!

I guess, this is a possible solution for longer battery use.

Here is discharge curve with 0.8V correction.
Correction could not be done easily by substracting the error, because below Battery voltage 3.5V, measurement begins rapidly grow. Device stops work at 3.4V.

It is difficult to name this device as a successful design.

Measured values are approximatelly 0.8V greater when WiFi or BT are used.

@ajb2k3 I see no answer to my question in this site. Maybe you could?

@felmue I draw schematic above from my exemplar. Obviously it's too old.
IC is SOT-23-5 and its marking corresond with MP1541 datasheet.

The root of the evil is M5STACK's absolutely lackadaisical documentation for all the products.

@ajb2k3 What Website?

Definitelly, M5SticC and M5SticC Plus have different schematics. DC-Boost in M5SticC Plus is sgm6603-5.

So, according to schematic switching off 5V is fundamentally impossible. IPSOUT via L1 and D3 allways present at output.

It's not a Schematic, it's a parody of a Schematic. Shame!

What is part # of DC-Boost IC for 5V out???

@felmue I tested it:
void AXP192::SetPeripherialsPower(uint8_t state) {
if (!state){
Write1Byte(0x10, Read8bit(0x10) & 0XFB);
Write1Byte(0x12, Read8bit(0x12) & 0XBF);
}
else if (state) {
Write1Byte(0x10, Read8bit(0x10) | 0X04);
Write1Byte(0x12, Read8bit(0x12) | 0X40);
}

EXT_BOOST_EN controlled correctly, DC-Boost stops generating, but bypassed input Vbatt to 5V output.

What an idiot designed this part of schematic?

I could not identify DC-Boost IC(Sot-23-5 marked IB3KB)/

@felmue It only switched 5V to Vbatt
I see the only way to reconnect EXT_BOOST_EN of the BOOST converter to VESP_3V3.

I tested it - does not work at all

Join the question
Obviously EXT_VDD is enabled via EXT_BOOST_EN pin of the AXP192, so it must be a way to control it.

Did anybody seen similar?
I have no idea how to repair.

I already wrote about poor documentation(
https://community.m5stack.com/topic/2482/ecg-module-code)
Now, I tested acquisition speed of the device.
Maximum data rate(DisplayECG() - OFF, delay(5) - OFF) is 66Hz.
And it could not be increased without changing onboard STM32 FW.
This uC acts as BLACK BOX. No description, no source code.
DisplayECG() - ON, delay(5) - OFF - 45Hz
Any serious ECG measurements started with data rate at least 250Hz.

Initially, I planned to use it with IR pulse sensor for Blood Pressure estimation. Obviously, with 15 mS accuracy it is impossible.

Make your own conclusions

It is very shame that the product is not accompanied with any documentation.
Where is the detailed schematic?
Where is the description of the FW?
Where is the description of RawDisplay SW?
Where is description of the passthrough serial?
Where is protocol description?

ECG Module13.2 detailed schematic mandatory
Block-diagram absolutely non informative

I post it here
https://github.com/m5stack/M5Core2/issues/40

Now Battery Coulombs are calculated correctly.