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timmers
- 19th June 2013, 23:52
Suggestions please for a serial monitor that can help me debug a project running at 562k5 baud (no it's not a typo 562,500 baud) with mixed parity.
I have an 18F26K22 communicating most of the time, but every now and then it drops the comms. Not sure if it is the PIC over running the serial buffer or the device simply re-establishing comms. The protocol is very capable but the PIC is almost max'ed out trying to keep up.

Baud: 562500
Parity: Even for header bytes, Odd for data bytes
Number of bytes: variable (min 5, max 64)
Time out period: 1mS
One byte is 19.5uS
PIC clock 54 Mhz (external clock)
Am running DT's instant interrupts.
Second serial port is running at a sedate 38k4.

I built an interface which commited the received data to RAM but it very quickly runs out of memory and gives only a snapshot of what is happening. I would need to monitor both RX and TX against time as it is full duplex.

HenrikOlsson
- 20th June 2013, 06:12
Hi,
There are a ton of serial port monitor/sniffer software around but they are usually aimed at sniffing communication going into and out of the PC on which the port monitor is running. If you're trying to sniff the communications between two devices where the PC running the sniffer software isn't one of them you'd need two serial ports and the software would need to keep the data in sync. I don't know any software that does this but I'm sure it exists.

Now, if you don't need to see the data in real time I'd suggest you get a LOGIC from Saleae. If I understand the problem correctly you could possible set an output when the serial timeout trips, trig the logic analyzer off of that signal and have it setup to have enough pre-trigger data stored to be able to see what was being sent back and forth between the devices. Another option is of course to just sample the data, store it and hope that it errors out before the memory runs out - which, depending on sample rate etc can actually be quite some time.

Unfortunately the LOGIC isn't able to trig off of specific serial data etc, (since it isn't analyzing it in real time) but it's still a VERY usable device IMO.

/Henrik.

timmers
- 20th June 2013, 10:12
One Logic16 ordered.
Thankyou Henrik.