https://www.embeddedts.com/products/TS-7800

TS-7800 by Technologic Systems

Specifications:
  * Marvell MV88F5182 500 MHz single-core ARM9 CPU
  * 128 MB RAM
  * 512 MB onboard NAND flash
  * SD & MicroSD slots
  * 2 SATA ports
  * Real-time clock (battery is dead on devices that I have)
  * 5 V @ 2W
  * Optional 8-30V input circuit (TS-781)
  * Rated temperature -20...+70 °C

I used these devices quite a lot around year 2010.

They are very useful to have a Linux host wake up and sleep on battery power. That's because they contain an AVR that can control the power and sleep for a certain amount of time (ts7800ctl utility).

The 500 MHz CPU is not too fast, and 128 MB RAM is not too much, but it's a lot for many applications. I used an Easycap USB video converter to get analog video from a video camera. Another application was logging some serial data once a day, otherwise consuming microamps when "sleeping".

I had done some kernel compiling for this platform for Yahoo! Group ts-7000, but the Yahoo! Groups discontinued their service, so the kernels may be hard to find from the internet.

I have also repaired one RTC to get an external coin cell battery for it.

This is how it looks like now:

{{ :ts7800_bat.jpg?400 |}}

While desoldering the RTC chip, I damaged the flash chip below and I had to reroute many traces with bare copper. Now, only SD card boot works and onboard flash was scrapped. That's OK. While opening up the RTC chip, I also damaged the quartz crystal, this was on one side of the RTC chip. On the other side, there is a capacitor (0.1 uF).

After adding the battery, the clock didn't start. The RTC registers showed that clock is stopped. I read the datasheet and I was guessing that had to put 0b010 (0x2) to OSC registers. This I did by modifying Linux driver rtc-m48t86.c temporarily.
I'm looking at the file a few years later and I guess I did something like this:

  ops->writebyte(0x20, M48T86_REG_A);
  printk(KERN_INFO "rtc binary 0x20 set ");
  
=====Links=====
  * https://www.digriz.org.uk/ts78xx/