This week I wrote the driver for the printer. Previously, we had been generating the cards using an Arduino because we were having issues with the interface to the receipt printer over the raspberry pi. There are couple of reasons I discovered as to why the receipt printer might not have been working before. First, the buad rate default for the interface we were using to talk to the printer was too slow. By fixing the baud rate, the printer and raspberry pi would be communicating at the same rate. Second, there is a limited buffer for the printer which needs to not be overfilled. By reading the Arduino library for interfacing with the printer, I discovered that there need to be delays inserted in order to prevent buffer overflows.
This week I was supposed to write the interface for the camera, but I didn’t get a chance to do that because we did not get the camera lens yet. As soon as we get the filter I will be able to productively write this interface.
Next week I am going to focus on writing the camera interface, even if we don’t have the lens yet. I’ll look at some open source examples to figure out the standard way for interfacing with raspberry pi camera modules.