nRF8001 wake up fails sometimes

[weil]

Hi,

I meet a very strange situation when I tried to wake up nRF8001 from sleep. I send 0x05 to nRF8001, it replies me ACI command 0x40 is unkown (0x82). I have checked sending buffer when I got this error, command is 0x05 indeed.

It happens randomly, like 1 out of 8 times.

[run_ar]

What MCU is this? and are you using ble-sdk-arduino? 0x40 is equal to 0x04 with the bytes switched. If you have access to a logic analyzer it would be interesting to see what is actually sent over the SPI interface.

[weil]

MCU is STM32F103RE. SDK is ble-sdk-arduino. The other commands are normal, actually BLE function is good. I am using lib_aci_wakeup(). I dont have logic analyzer for now. guess if there is anything else to do before sending waking up command?

[run_ar]

How much time does it take from you send the sleep command until you send the wakeup command? What 32KHz clock source do you use for the nRF8001?

[weil]

more than 10 seconds. Internal 32KHz clock source

[run_ar]

And you are using a crystal as 16MHz source as well? Are the ACI lines in a defined state while the chip is sleeping? The chip will be woken by the REQN line, so this has to be held high during the sleep period.