TS-7970 RTC WDT and Kernel updates

Notice Id: 205
URL: https://pcs.embeddedts.com/notices/ts-7970-rtc-wdt-and-kernel-updates Type: BOM Update
Contains Board Revisions: Yes
Effective On: Feb 20, 2023
Published: Feb 20, 2023
Products Affected: TS-7970

Dear Valued Customer,

We are contacting you today to notify you of a change in regards to Real Time Clock (RTC), Watchdog Timer (WDT), and Kernel updates on the TS-7970 from embeddedTS.  The RTC change is a software based algorithm to enhance accuracy of the Renesas Microtroller’s RTC,  the WDT change is a BOM modification to improve the startup stability of the WDT, and the kernel updates are part of our on-going improvements and forward looking development. The new Kernel is available as a separate download, there are no Kernel changes to the shipping software on the TS-7970 Rev. H.

The affected products are: TS-7970

We have updated the board revision for the TS-7970 to Rev. H as previously announced, which includes a change in the RTC component from the Intersil ISL12020 to the Renesas microcontroller's RTC. While the register set and software compatibility remain the same, the microcontroller’s inherent accuracy is ±20 ppm compared to the previous ±5 ppm. However, to improve the accuracy on the new RTC implementation, we have developed a calibration method that significantly reduces drift. This will be performed on all boards during production at room temperature. For more information, refer to the manual:

https://docs.embeddedts.com/TS-7970#RTC_Calibration

As a part of this new PCB revision we have found that on rare occasions the WDT in the CPU was incorrectly clocked. The Rev. H PCB moved to using the i.MX6 CPU's internal oscillator to drive the WDT. We have identified a potential situation where the internal oscillator may not start up correctly and the WDT will misbehave and either not fire or would reset the CPU at inappropriate times.

The BOM modification ensures that the internal oscillator will correctly start up at CPU power-on. The internal oscillator has a lower accuracy than the previously used external clock, and if an application feeds the watchdog too little it may need to be increased. Most daemons, like systemd or watchdogd, feed constantly and are unaffected by this change. See the manual for more details for feeding instructions:

https://docs.embeddedts.com/TS-7970#Watchdog

As part of our long term software support we have published a new 5.10 kernel which will receive security updates until December 2026.

https://github.com/embeddedTS/linux-lts/tree/linux-5.10.y

As we approach the next Debian release we will publish an early Debian 12 "Bookworm" image using this kernel. This will include updates to the manual on how to compile this kernel when this is ready.

Please contact us f you have any questions regarding the change to the TS-7970 Rev. H PCB or the BOM change indicated above.

We at embeddedTS appreciate your business. If you have further questions or concerns, please contact us by either replying to this email or by filling out the "Contact Us" form at support.embeddedts.com.

Best Regards,

embeddedTS
16525 East Laser Drive
Fountain Hills, AZ 85268
T: (480) 837-5200