LPC MicrocontrollersのトピックRe: I2C Slave with power saving

I2C Slave with power saving

frank-lin-Sunon — Fri, 07 Jan 2022 06:00:38 GMT

Hi,
I am using LPC802 and trying to use it as an i2c slave device.
I had already build a project with out power saving and work good.
But when i trying to let it go into power-down mode, it works strange.
Is there any sample for me to study?

attach file is the code i'm using.

Re: I2C Slave with power saving

ZhangJennie — Mon, 10 Jan 2022 06:45:00 GMT

Hi frank-lin-Sunon

I2C slave can wake up Power Down mode. We need to make sure I2C interrupt is enabled.

Regarding to demo code. Under MCUXpresso SDK, there is power_mode_switch_lpc. This demo doesn't include exact I2C wakeup. the demo wakeup sources are :

1. PB3,wakeup key

2. Wkt timer

3. PB2, reset key

You can refer them are reference.

Have a nice day,

Jun Zhang

Re: I2C Slave with power saving

frank-lin-Sunon — Mon, 10 Jan 2022 07:26:47 GMT

I had try using gpio wake up from power-down mode and delay about 10ms to get i2c signal.
It can wake up, but often return nack at address or all 0 bit when master try to read data (never work).

What setting do i have to do to let i2c can wake up mcu in power-down mode?

I had read the code of AN12125 and surprise it didn't include power saving.

Re: I2C Slave with power saving

ZhangJennie — Tue, 11 Jan 2022 08:06:00 GMT

Hi frank-lin-Sunon

Please make sure you follow the right process before enter power down mode. especially configure FRO as main clock

besides, please also make sure if you well configure I2C as wake up

when checking, use logic analyzer to measure I2C clock and data, if there is correct signal there.

Hope this helps,

Jun Zhang

Re: I2C Slave with power saving

frank-lin-Sunon — Wed, 19 Jan 2022 08:25:29 GMT

I change the code to

LPC_SYSCON->BODCTRL = 0;

PowerDown();

LPC_SYSCON->BODCTRL |= 1 << 4;

and everything runs good.