reading garbage from serial port PiTInfo

[JohnDoe]

I'm trying to get a PiTInfo v1.0 to work on a freshly installed Jessie on my Raspberry PI, but for reasons that escape me, I can only read garbage.

As far as I can tell, the console on serial port is disabled:

cat /boot/cmdline.txt 
dwc_otg.lpm_enable=0 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait

I've got a link to ttyS0

sudo ln -s /dev/ttyAMA0 /dev/ttyS0

I've set the serial port:

stty 1200 cs7 evenp cstopb -igncr -inlcr -brkint -icrnl -opost -isig -icanon -iexten -F /dev/ttyAMA0

and yet what I read is not what I'm expecting:

cat /dev/ttyAMA0
BPT@3L623@1|
G]JF8Ic 
@*.5 |
8j@6M&S
8
0LS c
.@*|
@rjE@1Va
@` @c
@0Ka
^C

Any pointers or help would be greatly appreciated.

[Charles]

@JohnDoe
Thing to check in order are :

• cable wiring and lenght
• remove any other devices already connected on téléinfo terminal block of ErdF counter
• did you solder the GPIO connector on the PITinfo board ?

then if it still doesn't work

• Change the 3.3K R1 resistor by a 1.2K
  

then if it still doesn't work

• remove the 1.2K and do a shunt.

Let me know these results, the last one should always works

[JohnDoe]

Wonderful. I really am impressed with how much effort you help people trying to follow your foot steps.

Some answers:

• I'll check the cable length; I don't like the cable I'm using now or how much slack there is; but I didn't think this might be an issue;
• there are no other devices - the PiTInfo connected is the only thing on the GPIO, and is directly connected to the EDF meter. There is nothing else;
• I bought the PiTInfo fully assembled;

Note that to check I just ordered a fully assembled PiTInfo v1.2 via Tindie from you - so we will see if this is a cable issue, a PiTInfo/hardware issue, or something else.

Updates to follow.

[Charles]

@JohnDoe
Excellent, we'll know if the changes made on 1.2 version solve your problem if it's coming from the output of your device (it should),

Just let us know, because I don't have a such device, everything always worked first time on my both counters here.

[JohnDoe]

@Charles New PiTInfo arrived, thanks! Installed and still the same thing happening. I also changed the cable from the PiTInfo to the meter. Output is still:

pi@raspberry ~ $ cat /dev/ttyAMA0 

GT` @ cPT@3Yn623@1|
gP0FP8Ic 
@*.5 L |
$8j@6N
$8
0H[	
        1F
`08
er 
`rjE@1PVa
@` ec
D0Ba
$@ 

Next things to try: a different Raspberry, perhaps an A or B+ (I've been using a Raspberry Pi 1 Model A+) then also revert back to Wheezy OS.

[Charles]

@JohnDoe
I don't rely too much on cat command
would you mind try a picocom -b 1200 -d 7 -p e -f n /dev/ttyAMA0 instead ?

[JohnDoe]

@Charles Sorry for the delay. I had a faulty SD card and couldn't figure out why making my bootable Wheezy SD card kept failing. Booted to Wheezy, adjusted the /boot/cmdline.txt file, /etc/inittab, and rebooted, but the cat command still yields the same results.

Here's the output of picocom:

picocom -b 1200 -d 7 -p e -f n /dev/ttyAMA0

 $8
 c 0[
 `08
    er 
       `rjE@8@a
               @S@ @c
"       @0|          P*
           $Rj
              ,
               &GT u @ cPT@3L623@1|
                                   gP0FPP8Ic 
                                             d*.5 H |
j                                                    $8j@6n$
  8
1F 0[
  (p08
      er 
         drjE@8@a
                 @S@ @c
"       @0jq           P*

 c!
   &GT q @ cPT@3L623@1|
                       G]JF8Ic!
                               d*.5 H |
j                                      $8j@6L$'
 $8
   0[   @ c
           (t08
               er 
                  @rjE@8P@a
                           @` ec
"       @0ja                     P*

Now I'm testing if it's a locale/codepage issue. What local are you using in your configurations?

[JohnDoe]

playing with code pages yields nothing - still only garbage - don't know where to look anymore

[JohnDoe]

@Charles It works! Why, I don't know. stty wants odd parity, picocom no parity. This is beyond me for now.

pi@raspberrypi ~ $ stty --file /dev/ttyAMA0 1200 cs7 ixon -parenb
pi@raspberrypi ~ $ cat /dev/ttyAMA0 
5
ADCO 012345678901 L
OPTARIF HC.. <
ISOUSC 30 9
HCHC 002698197 0
HCHP 010687090 2
PTEC HP..  
IINST 003 Z
IMAX 038 J
PAPP 00680 /
HHPHC A ,
MOTDETAT 000000 B

or with picocom:

pi@raspberrypi ~ $ picocom --baud 1200 --flow x --parity n --databits 7 /dev/ttyAMA0
picocom v1.7

port is        : /dev/ttyAMA0
flowcontrol    : xon/xoff
baudrate is    : 1200
parity is      : none
databits are   : 7
escape is      : C-a
local echo is  : no
noinit is      : no
noreset is     : no
nolock is      : no
send_cmd is    : sz -vv
receive_cmd is : rz -vv
imap is        : 
omap is        : 
emap is        : crcrlf,delbs,

Terminal ready
&4Nc
    HCHC 002698197 0
HCHP 010687195 8
PTEC HP..  
IINST 012 Z
IMAX 038 J
PAPP 02840 /
HHPHC A ,
MOTDETAT 000000 
Thanks for using picocom

[Charles]

Good it works, but the 1st time I see two linux programs that need different config to work on the same serial port !!!
would be interesting to know what node red want