Hello, nice to meet you all here.
Hendrik, I believe we are using the same schematic. You mentioned you had a problem communicating, receiving an "OK" after the "AT" is sent. I had my
Sagem NC board communicating fine, and sending SMS, etc.. everything great. But
now the communication seems to have locked up. I mean, I send just "AT" and get nothing back. I hooked a LA up between the MAX3232 and the Sagem, and the TX data from the PC is getting to the Sagem, and the Sagem is sending CTS active (low voltage some of the time). But, there is no RXD coming back out of the Sagem to respond with "OK"... very strange.
I noticed in a Hilo NC app not it says...
"Current re-injection appears when the module is off or not powered and I/Os connected to the module still
powered. Example: UART bus powered from the DTE side before the module is powered. This can result in a
bad starting behaviour.
To avoid current re-injection, simply do not supply the lines connected to the module before the module
switches on. Power up the module first using the Pok_in Line then open the UART lines for the DTE side and
all necessary I/O, this will avoid leakage of current improving the power consumption and avoid any possible
deadlock issue during the power up process."
Is this something that you might have been experiencing? Think I might be seeing the phenomena (deadlock).
In my case I was keeping the serial interface to the PC connected whilst powering up and down with a lab supply.. just can't believe that could have caused this issue.
My network "status" LED is blinking away and therefore I believe the module might be alive and well... other than the communication of course
Thanks for any help.. since it was working very nicely before, it is doubly annoying that it has just decided to STOP working now
-Robert (in Issan)
Added after 42 minutes:
This is also from the HiloNC app note....
" If a Level shifter is used or a RS232 adapter, use the VGPIO signal as the enable signal to avoid any
current re-injection before the module start."