HC-11 RF module UART working but no response to AT commands

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Hii back again with mysterious things;

I have for a while (dormant part project)
had 2 modules lying around. I know I successfully tested an ran these while back. One is attached to a m8 on uart on a pcb. Sendig some hello and retuning anything recieved. The other on a uart usb on the pc running putty for com.
For uart part it works ok, sent texts seen on putty terminal, and obidiently returns text sent to it(ie pbc m8, thats from pc connected hc to hc attached ocb m8, comes back to pc hc and to putty).
BUT it doesnt respond anything to at commands. When the pin on module for invoking AT is set low, the uart stops (which should be) but I cant provoke it to respnd to anything enterd.
Tried; AT,+AT,#AT, at,+at,...
I also shifted the two modules, if there was some issue with one...
Where am I going wrong.. Any ideas

Last Edited: Fri. Oct 18, 2019 - 06:54 PM
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gechxx wrote:
it doesnt respond anything to at commands

Not sure what "it" we're talking about here!

 

please post a diagram(s) to clarify.

 

if you need a tool for doing diagrams, see:

 

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Top Tips:

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  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
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Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
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Yes the same, almost. All components and placements same as what can be seen, however the texting on the pcb differs. Mine is less texted. Some clone.

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So here we go with supercad;

 

+--------------------------+

!    PC                          !  +------------------+                +----------------------+                                   +-----------------+        +-------------------------+

!                                   ! =! USB-UART   rx       --      tx                             !                                    !                       tx   -- rx                                  !

!      +-------------+       !  !                           tx      --      rx          HC-11       ! ------Y    ~~~       Y---!    HC-11       rx  -- tx            UART pins   !

!      ! putty         !        !  !                          vcc      --    vcc                           !                                   !                     vcc  --  vcc           on M8        !

!      ! window   !        !  !                          gnd      --   gnd                           !                                   !                    gnd  -- gnd                               !

+------------------------+ +------------------+            +-- < cmd-set                !                                   !                   cmd       +-------------------------+

                                                                               !     +----------------------+                                   +------------------+

                                                                               !

                                                                              v

                                                                            gnd

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It needs a mono-spaced font for ASCII-art to work - You need to post it as for source code:  see Tip #1.

 

Note that there is a 'Preview' button (next to the 'Post' button) to check how it looks before posting ...

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  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
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gechxx wrote:

Where am I going wrong.. Any ideas

Maybe it needs both CR and LF (\r\n) to terminate the command but you're only sending CR (or only sending LF) ?

(A complete guess, I've never used one of these things)

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ok thanks, will check

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Standard AT commands only require a one second idle pause, then AT<cr>   :note upper case AT

If echo is enabled then the modem will send back AT<cr><lf>  and if the command was taken then OK<cr><lf>

If modem is in transparent data mode, then one second of idle followed by +++ and another second of idle will escape data mode and return to command mode.

Jim

 

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Last Edited: Fri. Oct 18, 2019 - 08:59 PM
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Tried, Im beginning to think they have intoduced a 'best before' in the firmw.
Really annoying, I have no recollect that there was any trouble at all previous time. Have also switched the usbuart, no diff.
Well if nothing else I will have to live with 4800bps on the conf channel..... pf previous.(factory set is 9600)

Last Edited: Fri. Oct 18, 2019 - 10:05 PM