I'm just starting to mess with the MSP430 and have some simple apps working fine. However, now I want to use it with an LCD and am trying to determine if I'm short on I/O. For sure, I'll need to use the 4-bit interface, and I also need 3 outputs for E, RW, and RS. On top of that, I need to talk to my computer over RS232, but not via the built-in COM port-over-USB.
I've been looking over the documentation and can't figure out which lines the onboard FET is using. The situation I'm in is, I'd like to debug my application, but then need the FET. If the FET uses the TX/RX lines, then I can't test my serial code.
So the questions I have are:
- What's the best documentation to look at to figure out the answer to my question? I've been Googling and reading the MSP430x2xx Family User's Guide.
- Do people typically break up applications on the MSP430 into more logical groups to get around I/O shortages, and then combine at the end and hope for the best? This is the approach I would typically use. For example, I could use a different set of lines for TX/RX to test the software serial feature in one application, then test the LCD w/o serial support in another application. Then at the end, I could reassign the TX/RX lines and combine the features.
Best Answer
One reason why the Launchpad is so cheap is because the chip it uses is a very low-end device, which is missing many useful peripherals such as a UART. You will find things much easier if you use one of the other, more capable, devices You will need a FET, of course, but they aren't all that expensive, and it is a very useful tool.
Pins 16 and 17 on the target device are used for debugging. It might be possible to use them in your application if they are isolated with resistors, Microchip recommends that solution for debugging their devices when the ICSP pins are in use.
Most people build software like that starting from a simple application using one peripheral, and then add the additional functionality to the same program. Combining programs can cause problems.
A useful resource for MSP430 development is this Yahoo MSP430 group.