improved program loading

A project log for EasySXB

EasySXB is a terminal/program loader designed for use with Western Design Center's SXB line of 65xx development boards.

joe7joe7 04/07/2016 at 16:360 Comments

Updated the program loading to be faster. Will try to get some new binaries up soon, but I like to test them first.

Never did any serial programming before this. The FTDI chip threw me off a little at first, as it requires a time delay after each USB transaction. 16ms has been reliable, but that's a pretty long time so it pays to try to send data in larger chunks.

It's also possible to raise the port speed of the SXB, which defaults to 9600 baud. The strategy:

1. Connect at the default speed.

2. Upload a small program that calls a built-in ROM routine to raise the port speed.

3. Disconnect, and reconnect at the higher speed.

This can be done automatically, but I ended up discarding the feature for now, because it didn't make the uploading faster.

However, the uploader sends relatively small chunks of data (remember the FTDI delay) so there may be room for improvement. I suspect the ROM code could also have it's own speed limitations, but I'm not sure about that yet.

Grab the ROM reference and assembly dumps here, must-have information for the SXB's: