Hi Vasile, I understand what you are saying. With a very small correction in the blink-a-led.py script I was able to add the following to the blink samples that have the option to use LVP and that have a PGM pin.
For those PICs it says: pragma target LVP ENABLED -- low voltage programming, pull PGM pin LOW for normal operation For all other PICs it remains: pragma target LVP ENABLED -- low voltage programming It is a small fix and I add this easily. Kind regards, Rob ________________________________ Van: [email protected] <[email protected]> namens vsurducan <[email protected]> Verzonden: donderdag 5 januari 2023 06:25 Aan: [email protected] <[email protected]> Onderwerp: Re: [jallib] USB_help Perhaps a note in the sample header should attention the user to read datasheet about the use of PGM pin and LVP bit when LVP programming is used? That will avoid other possible situations for not tested microcontrollers using various types of programmers HW. For example the user is not disconnecting the programmer, has a pull down on his HW but the programmer has a pull-up on PGM. The combination may create an erratic voltage on PGM (not low but also not high) if the user does not disconnect the programmer cable before use... It seems to me that LVP is not about library but about programming. On Wed 4 Jan 2023, 7:50 PM Rob CJ <[email protected]<mailto:[email protected]> wrote: Hi Vasile, OK, so PGM should either be low (no LVP) or high (LVP) and not floating. This means that for these PIC's - with PGM pin- there should be a note added to the programming mode. For example: pragma target LVP ENABLED -- low voltage programming. Note: PGM pin must be HIGH pragma target LVP DISABLED -- no low voltage programming. Note: PGM pin must be LOW Agree? Kind regards, Rob ________________________________ Van: [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>> namens vsurducan <[email protected]<mailto:[email protected]>> Verzonden: woensdag 4 januari 2023 07:49 Aan: [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>> Onderwerp: Re: [jallib] USB_help To avoid entering in lvp mode by mistake at powering up, a pull down was used on PGM. It was a long discussion on Microchip or piclist forum about using pickit2 in lvp mode (using aux output). On Wed 4 Jan 2023, 8:15 AM vsurducan <[email protected]<mailto:[email protected]> wrote: On old PiC16F877, entering in lvp mode hapened with a low to high transition on LVP pin. I remember pull-up was used, but pull-down seems also ok. On Tue 3 Jan 2023, 6:36 PM Rob CJ <[email protected]<mailto:[email protected]> wrote: Hi RobH, If the default of the samples (and user programs) would be to enable LVP then the warning comment should then be to have a pull-up resistor on the PGM pin or am I interpreting the datasheet wrong? Kind regards, Rob ________________________________ Van: [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>> namens Rob Hamerling <[email protected]<mailto:[email protected]>> Verzonden: dinsdag 3 januari 2023 16:59 Aan: [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>> Onderwerp: Re: [jallib] USB_help Hi RobJ, On 03/01/2023 15.33, [email protected]<mailto:[email protected]> wrote: I had an e-mail discussion with the other Rob since he also had programming issues using LVP. It seems that for some (older?) PICs that have LVP only work if you pull a special PGM pin high (so not floating) with a resistor. I'm afraid I have to correct this: When LVP is enabled and the PIC has a Pin_PGM, this pin requires a pull_down resistor to prevent the PIC entering LVP mode accidentally. In order to prevent issues I could check which PICs have this PGM pin and for those PICs create only blink samples with LVP disabled. Another option is to enable LVP and mention in the blink sample comment to pull the PGM pin high for those PICs. The pull-down requirement applies to every program, not only samples also user programs. The reason (at least one of 'm) to specify LVP ENABLE in Jallib (blink) samples was that it allows the use the Microchip SNAP programmer (or any other LVP programmer) besides any HVP programmer like PicKit3. So my vote would be for adding a warning comment. Regards, Rob. -- Rob Hamerling, Vianen, NL -- You received this message because you are subscribed to the Google Groups "jallib" group. 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