Python am03127.py -p /dev/AMA0 -v -message Hello I had to install the python-serial library before using it, but then it worked very well. One tool that is great for driving the sign programmatically is the sample python code mentioned above. If this doesn’t work, you’ll need to get debugging and checking cables, etc. Ideally, use the remote control to reset the display first (FUNCT -> Setup -> Clear All -> Enter) Of course, you will never see the returned acknowledgement or results, but whatever text was on the display should now be dimmed. To use, simply cat these files to the serial port: cat id.cmd > /dev/ttyAMA0 The 04 is a checksum value and will depend on the command given. The second command sets the display to its dimmest setting. The first sets the ID of the display to 01 (the display ID can be anything from 01 to FF, 00 means broadcast to all connected displays). There are good instructions for that here.Įxample – to set the ID and dim the display, create two text files with the following in them: id.cmd: Unfortunately it is not possible to test this with a simple terminal program such as minicom, as the time between key presses is too much for the protocol to be followed (I guess if you had it line buffered it might work, but I didn’t look into this), but it is possible to “cat” some commands to the display to see if it is all working ok.Īlso, you need to have disabled the RPi console, which by default will be attached to the serial port. So once you realise that everything connects to the same labelled pin, you should be fine. So, the resulting combination of pins to connectors to wires to sockets is as follows: RPI GPIO I think that sort of follows the diagram in the manual, but the cable colours of my telephone lead didn’t match that at all. The combination that worked for me was linking TXD on the display to TXD on the DB9 socket, RXD to RXD and GND to GND. I had an old RJ11 to RJ11 telephone cable, so I ripped the plug off one end and set about working out which wires go where. The manual for the LED sign shows the socket view as follows: So, then I needed to decipher the pin-outs for the RJ socket on the display. Thankfully these are trivial to find based on the MAX3232 chip, so I got one that includes a built-in DB9 port and 4 pin connections for VCC, RXD, TXD, GND.įor some reason, these all seem to come with a female DB9 port, so I guess they are designed to link to a PC as if the jumper wires and MAX3232 breakout board make the equivalent of a null modem cable between the Pi and the PC. A project to add a Bluetooth interface to the display, by hardware hacking in an Arduino mini board – īut what I wanted to do was drive this from the on-board GPIO UART from the Raspberry Pi, and I couldn’t find an obvious description of what was required to make this happen.Īfter much reading, searching and a bit of experimentation, eventually I managed to assemble all the bits and work through the joys of the many standard RS232 pin-outs for DB9 connectors and the non-standard RS232 pin-outs for RJ11 connectors and come up with the following.įirst, to get to any kind of standard RS232 port from the GPIO UART a level shifter is required to go from the 3.3/5v RPi I/O to the +-12v required for RS232 serial ports.But most importantly, this contains the technical manual for the N00GA which details the serial protocol.Java code to drive the N00GA as a Twitter display (no longer works with recent Twitter API) –.Python module for AM03127 based displays (which this is) –.Now there are some excellent resources out there for programming these signs, see: The original sign is supposed to come with a USB to DB9 Serial and then DB9 Serial to RJ11 set of leads to allow you to connect the sign to a PC, but mine doesn’t have these. This has a serial port connection so I wanted to hook this up to my Raspberry Pi. I have a tri-colour LED matrix sign from Maplins (a bit like this one) that has an 80×7 two-colour LED display (red and green, and when both are on, a kind of orange).
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