On Tue, Jan 28, 2020 at 05:22:08PM +0100, Bernd Walter wrote: > On Tue, Jan 28, 2020 at 12:40:12PM -0300, Alan Carvalho de Assis wrote: > > Hi Bernd, > > > > On 1/28/20, Bernd Walter <be...@bwct.de> wrote: > > > I have had problens with a new SAM4S based board in that it hang eraly > > > during startup, before initializing my 12MHz xtal. > > > Also the SWD didn't work anymore until I erased the chip. > > > Since the SWD didn't work it was quite obvious that there is some clock > > > related issue. > > > I've found out that the startup code unconditionally switches to an > > > external 32kHz xtal. > > > On my board I didn't need one. > > > Interestingly I had no such problem on a SAM4E board, but there is > > > a small difference between those boards in that the SAM4E has XIN32/XOU3 > > > pins unconnected and the SAM4S has XIN32 used as GPIO. > > > Or maybe the SAM4E just behave differently when trying to init an unhooked > > > 32kHz xtal. > > > However, after commenting the sam_supcsetup() call my board worked fine. > > > I think there should be an option to initialize the 32kHz xtal or not. > > > > > > > Please check how other boards are doing it. Normally you have a DEFINE > > USE_CLOCK_XYZ inside the boardname/include/board.h. > > Ok - will do that. > > > I faced an issue similar to your on SAMD21, it was defined to use > > external crystal, but my board didn't have one. When I enabled the > > internal clock the serial console wasn't working correctly. Then > > Alexander noticed that it was missing a function to read the NVRAM > > calibration data to use with the internal RC clock. > > I have had the same problem with wrong uart clock on a few identic SAMD21 > boards, but results were different. > My board had been running on internal RC without USB. > An external 12MHz xtal existed, but I hadn't used it because of lazyness. > My problem however wasn't the RC, because after switching to the xtal > the problem still existed. > In my case it was the DFLL and everything was fine after switching to > the DPLL. > The DPLL however is not an option if you want to use the RC and > still being able to run device USB.
Oh - by the way. When you use an extarnal xtal on a SAMD21 disable the oscillator power saving feature (BOARD_DPLL_LPEN/SYSCTRL_DPLLCTRLB_LPEN) while debugging. The amplitude is insanely low and I couldn't see it swinging on my scope. -- B.Walter <be...@bwct.de> http://www.bwct.de Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.
