Hi,
I have a SPI sensor on an nRF51822, developed in mBED. To save battery power, I want to disable SPI while in ble.waitForEvent(). The only reference I could find is an nRF call:
NRF_SPI0->ENABLE = 0;
When I do that, two things happen:
1) Sensor no longer works when I wake up (I need to figure out how to properly re-enable and re-initizlie the sensor)
2) More importantly, sleep current still at 300uA instead of under 4uA.
Am I improperly disabling SPI with this command? I found it in the devzone forum, and maybe mBED needs to be performed differently? I want to solve the power consumption issue first. I've tested the code when not initilizing the SPI peripheral at all and things work correctly - I get under 4uA with the same sensor still attached. So I don't think the sensor is consuming that much by itself. I think the SPI peripheral isn't turning off properly, even though the SPI commands no longer function after wakeup.
This is a cross post on my mBED question here, where I post the code:
https://os.mbed.com/questions/81457/how-to-disable-SPI-for-power-savings-nRF/
#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()
