topic Re: Current threshold and Ah counter threshold sample code in S12 / MagniV Microcontrollers

Current threshold and Ah counter threshold sample code

gumu — Thu, 20 Jul 2023 09:25:42 GMT

Hi NXP team,

I'm using RD9Z1-638 to develop BMS project.There is a demand that device can be woke up from stop mode by current threshold or Ah counter.

This is my code:

u8 CAN_status[3]; Sleep_CAN(CAN0, CMPTX); // request CAN channel 0 go to sleep with completing transmission scheduled do { Check_CAN_Status(CAN0, CAN_status); // read the channel 0 status } while (!(CAN_status[1] & SLPAK)); // wait till SLPAK bit set B_PCR_WUEH_WUPTB4 = 1; // enable PTB4 wakeup B_ACQ_CTH = 100; B_PCR_WUEH_WUAHTH = 1; //Wake-up on Ah counter enabled B_GPIO_TSENSE = 0; B_GPIO_VSENSE = 0; ADCDisable(); TsenseDisable(); CAN_STDBY(STANDBYMODE); ApiRtcSetWakeupPeriod(RTC_PERIOD_WAKE_TIME); PCREnterStopMode(); ......

but it didn't work.

I'd like to know if there is sample code for this function!

Thanks!

Re: Current threshold and Ah counter threshold sample code

Q_man — Fri, 21 Jul 2023 06:07:46 GMT

To use any current sense based wakeup, the ISENSE channel must be configured and enabled in the Low Power mode. Here some example code:

ADCDisable(); 
TsenseDisable();
B_GPIO_VSENSE = 0;
IrqDisable();

// config to measure every 100ms in sleep
B_ACQ_TCMP = 100; // LP clock = 1KHz, depends on PF[1:0] setting

// config to wakeup if |I| > 500mA
B_ACQ_CTH = (500>>1);
B_ACQ_THF = 0; 

// config to wakeup if Ah counter >xxx
B_ACQ_CTL = B_ACQ_CTL_AHCRM_MASK | B_ACQ_CTL_AHCR_MASK; // reset Ah counter
B_ACQ_AHTH = 60000L; // 100mA * 60s * 10S/s

ADCLpEnable(); 
PCREnterStopMode();


//////////////////////
//---------------------------------------------------------------------
/*! \brief Enables CSENSE channel Acquisitions for low power modes.

*/
void ADCLpEnable(void) {

B_ACQ_CTL = (B_ACQ_CTL_CMENM_MASK | B_ACQ_CTL_CMEN_MASK)//!< enable current sense measurements
}

Re: Current threshold and Ah counter threshold sample code

gumu — Wed, 26 Jul 2023 06:36:36 GMT

Hi @Q_man ,

Thank you very much!

The sample code can work well. But I don't understand how to caculate the value of B_ACQ_AHTH ,

B_ACQ_AHTH = 60000L; // 100mA * 60s * 10S/s

what's the unit of B_ACQ_AHTH.

Thanks!

Re: Current threshold and Ah counter threshold sample code

Q_man — Thu, 27 Jul 2023 06:52:59 GMT

The coulomb counter (CC) simply adds up every ISENSE ADC measurement. The frequency (interval) of the measurements in low power mode can be configured with the ACQ_TCMP register.

In the example:

The frequency is 10 samples per second 10S/s. The ADC typically has a resolution of 1mA per LSB. This results in a 0.1mA*s per LSB resolution for the CC.

The threshold of 60000 equals to 6000mA*s (e.g. applying 100mA for 60s should trigger the threshold)