//e SSC weirdness

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Witchy's picture
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//e SSC weirdness

Hi folks,

I'm toying with A2CLOUD and/or ADTPro on a Raspberry Pi with a USB -> serial converter and the results I'm seeing with the serial transfer are odd.

Kit list:

//e with SSC set to 'terminal'
RPi B running A2CLOUD (based on debian Wheezy)
2 USB -> serial adapters, one with an FTDI chip and the other with the CH340 Chinese clone, both give the same result
hand-wired straight through cable with GND/Tx/Rx (also DTR/CTS available)

(disclaimer: if I use the same //e & SSC connected to an XP PC with real serial port and real serial cable it all works flawlessly so this is a linux->SSC issue I think - if I jumper Tx/Rx on the USB adapters together I get back what I typed in minicom...)

On the //e if I use IN#2 to select the SSC followed by CTRL-A 14B to allow direct input from the Pi via minicom the ASCII table appears to be consistently wrong and I haven't found a pattern yet. Serial comms are 9600 8N1 and with both USB -> serial adapters I get the following:

a becomes O
b becomes "
c becomes N
(d is an escape sequence)
e becomes M
f becomes &

this is consistent and can be reproduced.

Any clues?

Cheers!

6502enhanced's picture
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Re: //e SSC weirdness

Which Raspberry is it that you use - mod. 2B or mod.3?

Witchy's picture
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Re: //e SSC weirdness

It's an old B but should that matter? I thought they all use the same USB chippery. I've got a 2+ and one of the new zeros I can try.

A

6502enhanced's picture
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Re: //e SSC weirdness

Some time ago I tried a mod.3 - that does not work!

Raspple supports: "Raspberry Pi A/A+/B/B+/2B" ( http://ivanx.com/rasppleii/ )

Witchy's picture
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Re: //e SSC weirdness

For yuks today I altered the SSC end of the cable to spoof CTS/RTS and DTR/DSR in case there was a hardware handshaking thing going on and connected up a Pi2 and got......exactly the same results.

I don't know what's more frustrating, that it doesn't work or that the results are consistently wrong. Bizarre.

I also have a CH340-based 'proper' USB adapter in that it has a 9-pin male end and that *nearly* works. Characters I type in minicom do appear on the //e but case is ignored and things like 'h' are always lower case while 'E' is upper.

All the writeups mention a Prolific chipset on the RS232 side of things which I've not looked for yet but it's the next thing to do.

cheers!

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Re: //e SSC weirdness

Sorry for coming late to this one. I've had my share of SSC problems in the past, and 'somehow' I eventually figure out a solution (but I can't always remember what the process is!)

Have you tried slower speeds? Start at 300bps with the Pi and see what kinds of results you get. If it's working well at 300, then step up to 1200, then 2400, etc.

Sounds like from your testing that the problem definitely lies in the Pi and/or the USB to serial cable.

I would also strongly suggest using the Pi's GPIO as a 'genuine' serial port, there are tutorials on the web that can help with this.

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