June 7, 2018

Software triggered reset

There is a nice way to do this on the BBB and even the Intel Galileo. I was at a loss for a long time on how to do this on the Allwinner H3.

A way to do this on the H3, was suggested to me by Arjan van Vught in June of 2018. Use the watchdog timer (not the trusted watchdog) to generate a reset using a short interval. I select a 0.5 second interval and this works like a charm.

Allwinner H3 (with Cortex A53)

The Allwinner H5 (which has a Cortex-A53 processor) has a nice way to do this, courtesy of the A53 processor. It has a RMR register Here "RMR" stands for "reset management register" and lets us do just what we want.

Other possibilities on the H3

I have never investigated the following, but it may provide another way.

The ARM Cortex-A7 in the H3 does not have an RMR register. It does however have a bunch of debug registers, including a "Device Power-down and Reset Control Register", which might do the trick:

This has a "reset request bit" that you set to 1 to request a warm reset. This could do the job -- but what exactly is a warm reset?

Have any comments? Questions? Drop me a line!

Tom's electronics pages / tom@mmto.org