Intializtion time(CUP reset, CPU Initialization, RF setting) of nRF51822

[H_Nakamura]

Hello, We developed the energy harvest application equipment with the HRM1017 module. The function is every simply as follows:

After initialization, CPU scans 4 I/O ports (pulled up) and read the status (High or Low). If the port is low then it sends an advertising packet with the port number of Low. We confirmed that the packet was sent correctly but the time which the first packet was sent from the power up seemed long. It may be appx 1 [sec].

As the application software doesn’t take such time, we guess that the initialization takes much time.

We referred (developer.mbed.org/.../ ). Does this initialization with the mbed take much time? If there is the way to improve the initialization time, please advise us.

Best regards, Nakamura

[Stefan Birnir Sverrisson]

Hi

What has the most effect on the nRF51 startup time are two things:

• The supply voltage. The startup time is longer when using low supply voltages, i.e. ~1.8V.
• When initializing the S110 softdevice with external 32kHz crystal, startup of the crystal can take a long time, up to 1 second worst case.

So a solution would be to start up the softdevice with the internal 32kHz RC instead, and/or to use higher supply voltage, e.g. 3.0V