From: Guenter Roeck Sent: Monday, December 13, 2021 2:58 PM >> From: Adam Thomson >> Sent: Monday, December 6, 2021 5:38 PM >>>> Thanks anyway, so now I know it must be >>>> problem with my DA9061 chip. >>>> >>>> @Adam >>>> Where can it come from? >>>> Can you give we a hint what to check? >>> >>> I've spoken internally and have been informed that this is down to the fact that >>> DA9061 runs only from an internal oscillator which may be slower. The indication >>> is that the values for TWDSCALE describe the window where if a kick/ping occurs >>> within that period then the watchdog is guaranteed *not* to timeout. The actual >>> timeout would be at some point after the selected timeout period, assuming no >>> ping/kick occurred. >>> >>> Table 8 in the datasheet specifies a minimum watchdog timeout of 2.5s (tWDMAX) >>> under specific operating conditions, so if the minimum 2s window was chosen >>> (TWDSCALE = 1) then earliest the watchdog would actually timeout, following a >>> ping, is 2.5s, assuming the conditions matched those described. >>> >>> If you have further questions it probably makes sense to contact Dialog/Renesas >>> support as they will be able to provide more detailed info on this. >> >> So a DA9061 runs only from an internal oscillator, whereas a DA9062 >> can run on either an internal or an external oscillator. So this >> means that the DA9061 timeout values are differ from the DA9062 >> with an external oscillator not only on my device but on all DA9061 >> devices. >> >> This are the values (in seconds) in comparison: >> DA9062 (from driver): 0 2 4 8 16 32 65 131 >> DA9061 (measured): 0 3 6 12 25 51 102 204 >> ================================================= >> Difference: 0 +1 +2 +4 +9 +19 +37 +73 >> >> In my opinion, the differences in the higher values are very huge. >> If I expect that the watchdog triggers and I have to wait more than >> a minute for that to happen I ask myself is there something wrong. >> >> @Andrej >> I guess, you are using an external oscillator, aren't you? >> >> @Adam >> Is there a way to check in the driver which oscillator is in use? >> >> @Maintainers >> Is in the driver a need to distinguish between an external and an >> internal oscillator to get the timeout values more accurate? >> > > It would be very desirable to get timeout values more accurate. > I would not want to dictate how to implement it, though. > It could be automatically detected if that is possible, there > could be a devicetree clock property providing the clock > frequency, or maybe there is some other solution. > > Guenter I am open for a good solution. Meanwhile I measured the timeout values of my 8 available DA9061 watchdogs. I derived the following formula from the given formula at the data sheet and the clock divider of 2^16: f = 2^(15+TWDSCALE) / t Formula check with the external oscillator (32kHz) TWDSCALE=7 @ 131s: f = 2^(15+7) / 131 = 32017Hz (=> should be OK) The timeouts of my 8 watchdogs (9061-AA) with TWDSCALE=7: t7 = 211s => 19878Hz t7 = 197s => 21291Hz t7 = 203s => 20662Hz t7 = 204s => 20560Hz t7 = 206s => 20361Hz t7 = 198s => 21662Hz t7 = 200s => 20972Hz According to the data sheet the internal oscillator should run at 25kHz. The average frequency of my 8 devices is 20.6kHz. Maybe the data sheet Clock value is a max value. The timeout difference on my 8 devices are 14s. So the values vary from device to device, and maybe there is also a temperature component. @Adam Is there a way to check which oscillator is in use? Is there a way to find the current oscillator frequency? Are there any other ideas/solutions to get the timeout values more accurate? Thanks and regards Christoph
