True. As far as the design for protection and voltage reference, there are hardware design approaches as Olin described here, there are also software design approaches implemented in PICKit2 with the newest firmware for short-circuit protection and calibrating the voltage reference (by using your multi-meter). Of course there are pros and cons on these different design approaches, such as cost, performance, etc. End users need make the decision based on their own applications. Funny ----- Original Message ---- From: Olin Lathrop To: Microcontroller discussion list - Public. Sent: Wednesday, October 31, 2007 1:33:44 PM Subject: Re: [PIC]: Need suggestions for off board programmer Funny NYPD wrote: >> There is a tradeoff between reliability and cost. The PicKit2 is at the >> lower end of both, whereas my USBProg >> (http://www.embedinc.com/products/eusb2) is at the higher end of both. >> For >> hobbyist the lower end probably makes more sense. For professionals the >> tradeoff is usually skewed the other way. > > My personal understanding is: it is the design makes the quality and > performance, not the price. Of course, but making a design more robust costs more (else the cheap ones would be doing it too and then it wouldn't be more robust). This is definitely true between the PicKit2 and the USBProg. For example, I took extra care in the design of the USBProg to make sure the output lines could be shorted to anywhere from 0 to 6 volts indefinitely without harm to the programmer while still keeping the output impedence close to 150 ohms. 150 ohms was a deliberate tradeoff to support high speed but minimize damage to the target circuit in case of a short. The USBProg also has a boost converter from the USB power that is eventually regulated down to run the control PIC at 5V regardless of what the USB power supply level is within its allowable range. USB power can be as low as 4.3V at the device if I remember right. Last time I looked, the PicKit2 used the USB power directly and used it as the reference voltage. Take a look at both circuits, and you will see a extra measure of care taken with the USBProg. That doesn't make the PicKit2 "wrong" or "worse", just at a different place along the price/robustness curve. Of course the extra switching power supply and other parts cost more. The USBProg volumes are also lower, so it should be no surprise its price is higher than that of the PicKit2. As I said before, for hobbyist this tradeoff may not be worth it. For professionals however, $45 more for a tool designed to take more abuse is often a no-brainer. ******************************************************************** Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products (978) 742-9014. Gold level PIC consultants since 2000. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist