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6 years, 6 months ago.
how to disable SPI for power savings, nRF51822
Hi, I'm using nRF51822 along with a SPI sensor. I'm following this example on MBED.
https://os.mbed.com/users/jejuho/code/VTT_NODEV3_LIS3DH/
When I go to sleep via ble.waitForEvent(), I'm consuming about 300uA. This should be closer to 4uA. Without any of the SPI code, I get around 4uA. I googled how to enable/disable it, but I'm not sure is that's proper.
Is this correct?
NRF_SPI0->ENABLE = 0; disable
NRF_SPI0->ENABLE = 1; enable
#include "mbed.h" #include "LIS3DH.h" #include "ble/BLE.h" #define MISO p4 #define CS p3 #define SCLK p7 static LIS3DH lis(MOSI, MISO, CS, SCLK); float x,y,z; InterruptIn button1(p1); //nRF51822 P0.0 AxesRaw_t accel_raw; bool flag_read_acc; //ISR for I/O interrupt void button1_int(void) { //set flag on interrupt flag_read_acc=1; int main () { //pc.baud(9600); //pc.printf("...started... \n\r"); //Initialize SPI interface SPI spi(MOSI, MISO, SCLK); spi.format(8,3); spi.frequency(8000000); BLE &ble = BLE::Instance(); ble.init(); //using this just for sleep //Initialize LIS3DH driver lis.InitLIS3DH(LIS3DH_NORMAL, LIS3DH_ODR_25Hz, LIS3DH_FULLSCALE_2); //Init Acc-sensor //enable threshold to generate interrupt lis.SetLIS3DHActivityDetection(10, LIS3DH_INT_MODE_6D_MOVEMENT, 1); //set interrupt pin button1.mode(PullDown); button1.rise(button1_int); lis.LIS3DH_ResetInt1Latch(); while (1) { if (flag_read_acc == 1) { //do stuff in this routine flag_read_acc=0; //reset flag }//end if flag lis.LIS3DH_ResetInt1Latch(); //move this to when you really want to release NRF_SPI0->ENABLE = 0; //disable SPI? ble.waitForEvent(); NRF_SPI0->ENABLE = 1; //re-enable SPI //Initialize LIS3DH driver lis.InitLIS3DH(LIS3DH_NORMAL, LIS3DH_ODR_25Hz, LIS3DH_FULLSCALE_2); //Init Acc-sensor //enable threshold to generate interrupt lis.SetLIS3DHActivityDetection(10, LIS3DH_INT_MODE_6D_MOVEMENT, 1); }//end while }//end main()
2 Answers
6 years, 2 months ago.
Hi Eric
Did you ever get this to work. I cant seem to get rid of the 400ua power consumption at sleep after I have used any SPI devices!?
6 years, 6 months ago.
Hello Eric,
Yes you are correct. I am not sure if you have seen this discussion post on the Nordic website when searching around, but it goes over the board’s low power modes in more detail:
Here is also their reference manual which details the enable/disable:
http://infocenter.nordicsemi.com/pdf/nRF51_RM_v3.0.pdf
Hope this answers your question!
-Karen, team Mbed
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Hi Eric
Did you ever get this to work. I cant seem to get rid of the 400ua power consumption at sleep after I have used any SPI devices!?
posted by Ben S 21 Oct 2018