Hi,
I have a small problem with the RTC on STM32MP153. From hardware point of view I'm able to see sine waveform on the resonator 32.768kHz which is connected to PC14, PC15.
I use the Openstlinux - kirkstone (openstlinux-5.15-yocto-kirkstone-mp1-v22.11.23).
I configure rtc section only in tfa file
clocks {
/* USER CODE BEGIN clocks */
clk_lsi: clk-lsi {
clock-frequency = <32000>;
};
clk_hsi: clk-hsi {
clock-frequency = <64000000>;
};
clk_csi: clk-csi {
clock-frequency = <4000000>;
};
clk_hse: clk-hse {
clock-frequency = <24000000>;
};
/* USER CODE END clocks */
/* USER CODE BEGIN clk_lse */
clk_lse: clk-lse {
st,drive = < LSEDRV_MEDIUM_HIGH >;
#clock-cells = <0>;
compatible = "fixed-clock";
clock-frequency = <32768>;
};
/* USER CODE END clk_lse */
/* USER CODE BEGIN clk_hse */
/* USER CODE END clk_hse */
};
...
&rcc{
status = "okay";
/* USER CODE BEGIN rcc */
/* USER CODE END rcc */
st,clksrc=<
CLK_MPU_PLL1P
CLK_AXI_PLL2P
CLK_MCU_HSI
CLK_PLL12_HSE
CLK_PLL3_HSE
CLK_PLL4_HSE
CLK_RTC_LSE
CLK_MCO1_DISABLED
CLK_MCO2_DISABLED
>;
st,clkdiv = <
1 /*MPU*/
0 /*AXI*/
0 /*MCU*/
0 /*APB1*/
0 /*APB2*/
0 /*APB3*/
1 /*APB4*/
2 /*APB5*/
0 /*RTC*/
0 /*MCO1*/
0 /*MCO2*/
>;
...
&rtc{
status = "okay";
/* USER CODE BEGIN rtc */
/* USER CODE END rtc */
};
after the system start I see in the console
[ 1.925447] stm32_rtc 5c004000.rtc: registered as rtc0
[ 1.929185] stm32_rtc 5c004000.rtc: setting system clock to 2024-06-13T10:28:55 UTC (1718274535)
[ 1.938524] stm32_rtc 5c004000.rtc: registered rev:1.2
I set the time using
date --set="Thu Jun 13 10:43:51 UTC 2024"
and store it into internal RTC using
hwclock --systohc --utc
So far without any troubles. So next before power down I wait a few minutes to check if the RTC still ongoing using
hwclock
working perfectly. Than after power down and waiting for instance 5 minutes I get old time, the time before the power down. It's seems to be the RTC not counting during power down. I check and sine waveform is generated during power down. Of course battery 3V is connected to VBAT pin.
Where to resolve this problem.
BR Michal
