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] 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] <[email protected]> namens Rob > Hamerling <[email protected]> > *Verzonden:* dinsdag 3 januari 2023 16:59 > *Aan:* [email protected] <[email protected]> > *Onderwerp:* Re: [jallib] USB_help > > > Hi RobJ, > > On 03/01/2023 15.33, [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 H*amerling, Vianen, NL > > -- > You received this message because you are subscribed to the Google Groups > "jallib" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/jallib/bcc403f2-6580-1d18-0d8a-25109e7a933d%40gmail.com > <https://groups.google.com/d/msgid/jallib/bcc403f2-6580-1d18-0d8a-25109e7a933d%40gmail.com?utm_medium=email&utm_source=footer> > . > > -- > You received this message because you are subscribed to the Google Groups > "jallib" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/jallib/GVXP195MB1637E54549EBC46A30C7266AE6F49%40GVXP195MB1637.EURP195.PROD.OUTLOOK.COM > <https://groups.google.com/d/msgid/jallib/GVXP195MB1637E54549EBC46A30C7266AE6F49%40GVXP195MB1637.EURP195.PROD.OUTLOOK.COM?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "jallib" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/jallib/CAM%2Bj4qtRBu9MiWwMhJQzN26vj0LGZNqZm2uhKxnwKsetYMmuhw%40mail.gmail.com.
