High power consumption with I2C G-sensor

[sam zhou]

We are using 51822 through I2C to get G-sensor buffer, every 560ms ( sample every 20ms, buffer for 28), then execute for step counter calculation, which should not consume much power. But the current measurement seeing, peak@4mA, rise to peak and down period last 150ms? sleep is working, but not sure why it took such long time to do so and peak @ 4mA? see picture below

we use twi_sw_master reference code

[sam zhou]

Don't think so. As we changed to SPI, the current drop down. So far, we guess it is caused by I2C, I did not see good result in this forum on I2C power. Future, will consider 52 series, with DMA, which wake CPU as less as possible.