On Mon, 14 Oct 2019 05:05:45 -0700 (PDT), in gmane.comp.hardware.beagleboard.user Mridul Ahuja <[email protected]> wrote:
> >I have a BeagleBone Black running *Debian 9.9 2019-08-03 4GB SD IoT *( >https://beagleboard.org/latest-images). I want to integrate it with Sim900a >GSM module. But I can't get the UART working. I've connected the pins P9.24 >(UART1 TX) to RX of the module, P9.26 (UART1 RX) to TX of the module, and >P9.2 (DGND) to Gnd of the module. Also I've configured the pins to work as >UART by using sudo config-pin P9.24 uart > >I've tried other UARTs also but no luck. Any help please ? Well... I suspect my first step would be to put an oscilloscope (or, if low enough baud rate, just some LED) on the Tx lead to see if anything is going out. Or even just a loop-back (jumper Tx to Rx, send some short string and see if the same string is received; I say "short" as you may need to ensure the reads interleave before any buffer overflows). Second concern... Based upon https://www.instructables.com/id/GSM-SIM900A-With-Arduino/ the module operates on 5V. The BBB is 3.3V device! If the module is putting out a 5V swing on its Tx you've a good chance of damaging the BBB Rx inputs (and conversely, the module may not be seeing any changes on its Rx). NOTE: if the module uses a pull-up to 5V on its Rx, you could be damaging the BBB Tx lines. HOWEVER, further down (Step 3 of the link) they mention "3VR, 3VT, 5Vr, 5VT, VCC and GND". That may indicate the module has both 5V and 3V pins. You MUST use the 3V pins with the BBB. What power supply are you providing to the module. You still need a 5V supply to the module. -- Dennis L Bieber -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/e1u8qehogleqc397j9vhs5ec0bhrb6n243%404ax.com.
