UFE New PCB Assembled and Working
Posted by retromaster on July 6, 2010
Over the last couple of weeks, I’ve managed to assemble the new UFE board and make the necessary changes to the firmware to make it work with the PIC32MX575. I’ve also mounted the board in the floppy slot of an A500 to see how it would actually look. The result is quite nice and it is quite practical to operate with the A500 top cover closed. I’ve had to hot glue a couple of threaded posts to the base of the A500 case to be able to screw the board, but other than that, no case modding is necessary.
I am a little disappointed with the PIC32MX575 though. First of all, the I2C module has an embarassing bug which causes the module not to assume control of the output pins properly. To add insult to injury, the workaround specified in the errata document seemed to be insufficient in my case. In addition to manually declaring the pins as output, they also needed to be configured as open-drain, otherwise it did not work. Another issue (that still remains unresolved), is that I could not get the “IDLE” power save mode to work properly. The behaviour here seems to be different than the PIC32MX460, but I could not figure out what exactly is different. The IDLE mode is used by the UI code to wait for the vertical blanking period for video output. The code that worked fine on the 460 does not seem to work on the 575, so I’ve had to (hopefully temporarily) replace the IDLE mode with busy-wait loops.
Nevertheless, most of the basic functions of the UFE work fine in the new board. There is one remaining problem with the write clock recovery circuit that I could not get the component values right. Hopefully, I should be able to sort out that problem tonight. Afterwards, the first order of business will be to create a video of the UFE in operation and put up a new project page for it.