Post by thread:16F877 Programming difficulties

Just a quick note in case this jogs anyone's memory: I'm trying to program a PIC16F877 on my board, it's a TQFP package, I have a 5X2 pin header for programming, identical setup to my last project using a 16F84 (jumpered for operation). I built a programming cable with a 40 pin socket on one end and a 5X1 plug for the header on the other, I'm using a Picstart+. Again, this is the same way I did it for the 16f84. 16F877s in a DIP package program just fine in the Picstart, but when I plug in the cable and plug that into a board I can't get it to program, I get various errors, including "Cannot Transmit", "Cannot Receive", just plain "Failure" in the program/verify window, and occasionally something like "Command 8F not echoed properly (F8)". Does anyone have any clue what might be wrong? Or suggestions on what to look for? The cable checks out fine with the ohmmeter, it's about 8 inches long and shielded, so should be electrically fine. I'm stumped. Dave Johnson

Can't help, but I can commiserate. I was just whining about this happening yesterday. We're using PICSTART Plus, also. Funny thing is, of three 877s on my desk, this is the only one to behave like this. Now, with the good ones, I did get a lot of "Cannot Transmit" Cannot Receive", etc. but they still take the bits. This particular specimen took the bits once just fine, then suddenly began reporting failure after finishing address 1FFF. A read indicates that the original successful (but buggy) code is still there. > > Just a quick note in case this jogs anyone's memory: > > I'm trying to program a PIC16F877 on my board, it's a TQFP package, I > have a 5X2 pin header for programming, identical setup to my > last project > using a 16F84 (jumpered for operation). > > I built a programming cable with a 40 pin socket on one end and a 5X1 > plug for the header on the other, I'm using a Picstart+. > Again, this is > the same way I did it for the 16f84. > > 16F877s in a DIP package program just fine in the Picstart, > but when I > plug in the cable and plug that into a board I can't get it > to program, I > get various errors, including "Cannot Transmit", "Cannot > Receive", just > plain "Failure" in the program/verify window, and > occasionally something > like "Command 8F not echoed properly (F8)". > > Does anyone have any clue what might be wrong? Or > suggestions on what to > look for? The cable checks out fine with the ohmmeter, it's about 8 > inches long and shielded, so should be electrically fine. > I'm stumped. > > Dave Johnson >

The Picstart+ is not designed for in circuit serial programming. It can do it under some circumstances but the drivers are not powerful enough to reliably work in this capacity. If there is other circuitry on your board that can pull the supply down. The best bet is a Promate with the ICSP adaptor. I know it is more expensive but it does work reliably as long as you follow the rules. At 02:18 PM 8/6/99 -0700, you wrote: {Quote hidden}>Just a quick note in case this jogs anyone's memory: > >I'm trying to program a PIC16F877 on my board, it's a TQFP package, I >have a 5X2 pin header for programming, identical setup to my last project >using a 16F84 (jumpered for operation). > >I built a programming cable with a 40 pin socket on one end and a 5X1 >plug for the header on the other, I'm using a Picstart+. Again, this is >the same way I did it for the 16f84. > >16F877s in a DIP package program just fine in the Picstart, but when I >plug in the cable and plug that into a board I can't get it to program, I >get various errors, including "Cannot Transmit", "Cannot Receive", just >plain "Failure" in the program/verify window, and occasionally something >like "Command 8F not echoed properly (F8)". > >Does anyone have any clue what might be wrong? Or suggestions on what to >look for? The cable checks out fine with the ohmmeter, it's about 8 >inches long and shielded, so should be electrically fine. I'm stumped. > >Dave Johnson > > Larry G. Nelson Sr. spam_OUTL.NelsonTakeThisOuTieee.org http://www.ultranet.com/~nr

At 11:02 3/09/99 -0400, you wrote: Make sure the LVP pin is help LOW on your target board. It is pin 36 on the 40-pin dip parts but you will have to look it up for your SMD part. Chances are this will see you right. -Jim {Quote hidden}> > >At 02:18 PM 8/6/99 -0700, you wrote: >>Just a quick note in case this jogs anyone's memory: >> >>I'm trying to program a PIC16F877 on my board, it's a TQFP package, I >>have a 5X2 pin header for programming, identical setup to my last project >>using a 16F84 (jumpered for operation). >> >>I built a programming cable with a 40 pin socket on one end and a 5X1 >>plug for the header on the other, I'm using a Picstart+. Again, this is >>the same way I did it for the 16f84. >> >>16F877s in a DIP package program just fine in the Picstart, but when I >>plug in the cable and plug that into a board I can't get it to program, I >>get various errors, including "Cannot Transmit", "Cannot Receive", just >>plain "Failure" in the program/verify window, and occasionally something >>like "Command 8F not echoed properly (F8)". >> >>Does anyone have any clue what might be wrong? Or suggestions on what to >>look for? The cable checks out fine with the ohmmeter, it's about 8 >>inches long and shielded, so should be electrically fine. I'm stumped. >> >>Dave Johnson >> >> >Larry G. Nelson Sr. >.....L.NelsonKILLspam@spam@ieee.org >http://www.ultranet.com/~nr > Regards, Jim Robertson NEWFOUND ELECTRONICS ________________________________________ Email: newfoundKILLspampipeline.com.au http://www.new-elect.com MPLAB compatible PIC programmers. ________________________________________