reading battery status via i2c always reports 0

[wez]

I'm not sure if I'm doing something wrong here, but I can read keyboard data and change the backlight just fine, so my i2c stuff generally works.

I have this rust function to read the battery register; it sends REG_ID_BAT and then reads back 2 bytes:

const KBD_ADDR: u8 = 0x1f;
const REG_ID_BKL: u8 = 0x05;
const REG_ID_FIF: u8 = 0x09;
const REG_ID_BK2: u8 = 0x0a;
const REG_ID_BAT: u8 = 0x0b;
const REG_WRITE: u8 = 1u8 << 7;

async fn read_battery_pct(
    i2c_bus: &mut I2c<'_, I2C1, embassy_rp::i2c::Async>,
) -> Result<u8, embassy_rp::i2c::Error> {
    let mut buf = [0u8; 2];
    i2c_bus
        .write_read_async(KBD_ADDR, [REG_ID_BAT], &mut buf)
        .await?;

    Ok(buf[1])
}

The data I get back is always [REG_ID_BAT, 0], which corresponds to:

PicoCalc/Code/picocalc_keyboard/picocalc_keyboard.ino

Lines 140 to 143 in 4c65694

	case REG_ID_BAT:{
	//Serial1.print("REG_ID_BAT getBatteryPercent:");Serial1.print(current_bat_pcnt);Serial1.println("%");
	write_buffer[0] = reg;
	write_buffer[1] = (uint8_t)current_bat_pcnt;

but with current_bat_pcnt set to 0.

That value always appears to be 0 for me; whether the batteries are installed, removed, charging or when the usb-c cable to the picocalc (not the pico) is attached to the computer or not.

Am I reading the schematic correctly? I think the STM MCU Serial1 is connected to UART1 (pins 8/9) on the pico, so I should be able to read the PMU debugging information by reading from that uart in my pico firmware? I capture and log that data, but I haven't seen anything get printed there so far.

Should I be doing something differently to read the battery level?

[wez]

Compiling and flashing the current version of the master branch fixed the reported battery level for me

[prokrypt]

Yep. Was fixed with 65bf0c6

[wez]

I found that I also needed #22 to read the charging status, too

[cuu]

#22 did not fix all but helped me to realized that current_bat_pcnt is not a good idea

when I try to fix in 65bf0c6 I totally forgot the reg of REG_ID_BAT

current battery percent can be stored in reg of REG_ID_BAT

So I will remove current_bat_pcnt from code later and add bitSet(percent,7) to indicate charging status just like @wez said

[cuu]

@wez

a1847ee

removed current_bat_pcnt now

I've updated picocalc_helloworld ,added new battery info code with charging status
in 3b84959

I also find out that, when I press the battery into socket for the first time, there is a slight time that axp2101 chip will report battery percent to be zero ,that causes low_bat() to do PMU.shutdown();

So I add a low_bat_count to debounce to avoid

[wez]

@cuu the code looks good! Regarding #22, I think the issue with the report_bat function still exists. Should I rebase that PR and re-submit, or do you have other plans for this?

[cuu]

@wez sorry I forgot the report_bat issue, now I commented out all report_bat calls, but allow me to leave the code

295f7e7