USB and PIC Microprocessor 18F2455
Microchip has come out with several new microprocessors for use with USB: 18F2455, 18F2550, 18F4455, 18F4550. These chips have many advantages over the first generation USB chips (read about the 16C745, and 16C765) and I would suggest using these chips for new projects. The key advantages of the 18F* series USB chips are:
- Full Speed USB - the 16C generation only supported low speed USB
- Flash programmable - instead of eprom which required a UV eraser
- Clock Speed - up to 48MHz instead of only 24MHz
Microchip has provided sample firmware for these chips that are likely very useful for developing projects. The firmware is available at Full Speed USB Solutions. Since the Microchip website changes frequently, this can be found by going to microchip.com, clicking on 'Technical Support' under 'Support', then clicking on 'Design Home Page' from the menu on the left, clicking on 'Application Design Centers', selecting 'USB' from the connectivity solutions, and finally picking 'Full-Speed USB'.
Updated to August, 2006
A number of helpful visitors emailed me regarding programmers for the 18F series chips in response to my posting below - all responses are very much appreciated. I'll quickly summarize the response I received. I have not had an opportunity to try any of these out so I'm just passing out what others have told me.
My requirements for a programmer are: 1) cheap; 2) USB support (rather than serial cable); 3) zif socket; 4) no external power supply.
- WinPic software with SCHAER+ hardware (parallel port). [Downloadable software and full schematics] My correspondent confirms that it works with the 18F2455, 18F2550, 18F4455 and 18F4550. thanks Nam
- A free hardware/software in-circuit programmer combination that lists support for the 18F USB chips. It is driven by the parallel port but I couldn't tell if it requires an external power supply. thanks PicNic (PicNic also has a list of programming options for 18F chips.)
- Another correspondent successfully used the WinPIC software (linked above) with a serial port programmer adapted from the EasyPIC (requires 5V power supply and serial port). thanks Aaron
- PVK40 is a development board/programmer that apparently supports the 18F chips. thanks Rodney
- Someone pointed me to the KitsRUs K128 PIC programmer (USB port). This is the programmer I have and it works great except it does not (yet) support the 18F series chips. UPDATE: dinger pointed me to DonkeyProg, a hack that allows a DIY programmer to program the full line of 18F chips. Unfortunately, the USB K128 is not supported although other programmers are.
- The Brenner5 from sprut has a parallel port controlled programmer with software. thanks Daniel
- PicStart Plus (from Microchip) can be upgraded with a small kit to support the 18F chips (newer versions are already upgraded). This is a serial port programmer but it was suggested that a Belkin F5U409TTCU USB->Serial Port convert ($50CDN) can be used to make it compatible with a USB only computer. thanks Michael
- Spark Fun Electronics sells a PIC programmer powered from USB which seems to support the 18F chips. It sells for $87USD. thanks Kavindra
- Microchip has come out with a new programmer PIC KIT 2 powered by USB and only $40USD. Thanks PicNIC for pointing this out.
If you have other suggestions, email me and I'll keep adding to the list. There seems to be enough programmers out there that do what I want to do, now it is just a matter of finding some time to get back into PIC programming and USB device development.
Update - as of August, 2005
I bought some of these chips but unfortunately the PIC programmer I have does not support these chips, yet. Originally, they said they would be supported by the end of June, 2005, but now it is into August and still no word. If someone can recommend a good, relatively cheap programmer for these chips, contact me. As soon as I get a working programmer, I will write more fully about these chips with downloadable code and working examples as I've done with the 16C745.