Pins 39, 40 are not 5V tolerant. You really shouldn't connect a 5V signal to them. They may already be damaged at this point. See this wiki page for information on how to interface the IOIO with 5V logic: https://github.com/ytai/ioio/wiki/Digital-IO Make sure to use 5V tolerant pins for both. You definitely need a pull-up to 5V on the output and might as well have one on the input. I totally don't get the design of the RX/TX circuit on the EFCOM schematic. Either it's totally weird or I'm missing some very clever trick. Definitely not a standard way of shifting voltage levels...
On Tue, Oct 27, 2015 at 3:06 AM, Andries Kruger <[email protected]> wrote: > Hi, > > I'm trying to integrate a GSM modem to my project (EFCOM PRO from Elec > Freaks). I can connect the module to my pc fine using a usb to uart > converter, send AT commands and receive the responses. > > When trying to connect it to the IOIO, I cannot receive the reply. I am > using pins 39 and 40 (tx and rx). Now I know that the modem replies > correctly as I have sent a command from the IOIO and received it using the > USB-UART converter and TeraTerm. > > I use the following code to set up my UART: > > //Setup Comms UART > DigitalInput.Spec rx = new DigitalInput.Spec(40, > DigitalInput.Spec.Mode.PULL_UP); > DigitalOutput.Spec tx = new > DigitalOutput.Spec(39,DigitalOutput.Spec.Mode.OPEN_DRAIN); > commsUart = ioio_.openUart(rx, tx, 9600, Uart.Parity.NONE, Uart.StopBits.ONE); > commsRx = commsUart.getInputStream(); > commsTx = commsUart.getOutputStream(); > > > Am I doing anything wrong here? Any advice or tips would be greatly > appreciated. > > -- > You received this message because you are subscribed to the Google Groups > "ioio-users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/ioio-users. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "ioio-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/ioio-users. For more options, visit https://groups.google.com/d/optout.
