THE SONG REMAINS THE SAME

I unplugged the 40-pin MPLAB ICE 2000 device adapter from the PICProto USB development board and plugged it into the 40-pin PIC16C765 socket on my PIDCEM USB development board. I clicked on the MPLAB IDE Run icon and, lo and behold, the PICProto USB development board demo code ran on the PICDEM USB as it should.

Although cosmetically modified to compile inside PicBasic Pro, the core USB code and fundamental hardware design are identical. The PICDEM USB development board differs from the ME Labs PICProto USB development board only in the amount of on-board equipment. The former comes assembled with a USB CD-ROM containing support code and documentation, a preprogrammed PIC16C765 full of demo code, a 3¢ USB A-B cable, a blank ’16C745, and a blank ’16C765 (see Photo 7). It also includes a serial port, a game port, a PS/2 keyboard/mouse port, enumeration status LEDs, and a backlit LCD landing pad.

Photo 7—If you prefer an assembled alternative to the PICProto USB, the Microchip PICDEM USB provides the basic functionality of the PICProto USB in addition to the ability to experiment with using USB to control an LCD and game pad. The PICDEM USB LEDs, which can be switched out with a jumper or at the firmware level, illuminate to signal each state of enumeration.

I wasn’t able to show you every detail of the USB traces, and I would need a few more pages to take a complete look at the features offered by the USB Tracker 110 and UsbShow. So, instead of leaving you hanging, I’ve included all the USB trace data that I took from the PICKit1 Flash starter kit, the PICProto USB, and the PICDEM USB. You may download the data from the Circuit Cellar ftp site. The core USB source code is on Microchip’s web site.

If you’re wondering how you’re going to read the USB traces, simply download your freeware copy of UsbShow (www.usbtracker.com). The UsbShow software will display the USB traces I’ve provided and the detail contained within them. However, you won’t be able to take your own USB traces without a USBTracker 110. The USB Tracker web site also has a great pictorial overview of what the USB Tracker 110 and UsbShow can do. Reviewing the overview will make it easier to interpret the USB traces. USB is complicated, but at least it’s embedded.