4 ms·
Interposer to fix the Symmetricom SyncServer S200 GPS week rollover problem
- userbinator 2y agoSeveral years ago I fixed an MTK GPS module in a smartphone with the same problem by RE'ing the firmware and patching the date boundary in it. I wonder if that's possible with this module too.
- floam 2y agoSeems this guy[0] could do just that if only he had access to a SyncServer S200? The very author of this blog post replied to the person and told them about his interposer solution, he’s not unaware. > It may also be possible to build similar patches for other units, such as the S200/S250. But currently I only have access to S350 and XLi. [0]: https://lists.febo.com/empathy/thread/UXOVZ2E4YGGNPSXLJSELLKOYGRB4ENPZ https://lists.febo.com/empathy/thread/UXOVZ2E4YGGNPSXLJSELLK...
- tverbeure 2y agoAlex’s solution doesn’t patch the module itself, but it patches the FW of the MCU in the SyncServer motherboard that drives the module. People have looked into patching the module itself, but I haven’t seen any progress on that. It’s possible that the M430 MCU doesn’t allow dumping of the FW that is stored in on-chip flash.
- francis_t_catte 2y agoI have a Symmetricom ExacTime ET6000 that had a Motorola Oncore M12+ mounted to an ACE-III interposer made by Synergy systems that hadn't suffered from a rollover yet, but instead had a 3 month leap second induced offset. I went the (mildly easier) route with a Furuno GT-8736D, then modifying the interposer with a level shifter for the serial lines as the ET6000 uses 5v TTL logic, and the Furuno chipset is only rated for 3.6v maximum (and so was the M12+, for that matter!).
- tverbeure 2y agoMy first board rev had level shifters too, but they weren’t needed in the end.
- ufocia 2y agoRP0 seems like such overkill for the problem. It's like shooting a mosquito with a howitzer.
- tverbeure 2y agoThey’re less than $1 on AliExpress and $4 on Amazon. Do you really want to spend time optimizing for something cheaper just because you don’t want to waste some MIPS?
- wildzzz 2y agoThe cost of buying an off the shelf GPS module to replace the original is so high that any price difference in microcontrollers or even an SoC is negligible. You could drop an entire raspberry pi in there and still be saving money.
- tverbeure 2y agoExactly. There’s also the fact that I have RP2040-Zeros ready to use in a drawer. They’re so convenient, tiny, cheap, still lots of pins, always enough performance, easy to program with just a USB cable. Any other MCU, and I’d have add power regulator, caps, coils and a USB connector. Add the cost of shipping from Mouser/Digikey (at least $5) or LCSC (long wait time) and it only makes sense for high volumes. IOW: never.
- zokier 2y agootoh you can just buy complete gps based ntp servers from china for <$100, so there is that too.
- tverbeure 2y agoI’ve seen them for $80 on eBay, and you could build something like that yourself with a $25 thin client[0] and a USB GPS dongle. But I doubt you’d have the local oscillator for hold over, you wouldn’t have the 10MHz and 1PPS inputs and outputs, and let’s not forget the lack of a cool looking case with VFD. :-) I have no need for an NTP server, this was just a fun deep dive into something I found at the electronics flea market. But there must be reasons why these things still go for much more than $80 on eBay after they’ve been upgraded with a new GPS module. [0] https://tomverbeure.github.io/2023/06/25/ThinMachine-a-Thin-Client-MacOS-Time-Machine-Appliance.html https://tomverbeure.github.io/2023/06/25/ThinMachine-a-Thin-...
- nullc 2y agoMy understanding is that someone has developed hacked firmware for the XLi, they're just not sure that they can lawfully distribute it.