HP488 confusion

[croudyj]

Hi,

I'm very impressed with the look of the E-Blocks system and I'm thinking of buying the HP488 as my first PIC programmer. However, before I do, I'd like to clear up some confusion. Regarding the LVP problem involving port B, I understand that if I want to use the LCD from a PIC that uses RB5 in LVP mode, I have to avoid LVP mode entirely. I further understand that this means I need a 13.5V supply. No problem. The confusion is this: in the manual for the HP488 it says the following:

"If LVP is disabled the programming software PPP will not be able to ID the on board PICmicro ... Then the PPP will indicate that the chip has not been erased. There is no point in continue to try to program the PICmicro."

I understand this to mean that the HP488 with PPP cannot use high-voltage programming mode. This can't be correct because it conflicts with other information about LVP.

I'd appreciate it if someone could please confirm that I will be able to program in high-voltage (13.5V) mode on a PIC that uses RB5 for LVP and further that I will be able to use the LCD properly. The device I am targeting is the PIC18F2550.

Thanks in advance for any light you can shed on this.

John

[Benj]

Hello John

The HP488 is capable of running high voltage programming with LVP disabled allowing for access to pin RB3 - RB5 depending on the chip. We also provide jumpers to allow chips using LVP to access the LCD via alternate pins on PortB.

I'd appreciate it if someone could please confirm that I will be able to program in high-voltage (13.5V) mode on a PIC that uses RB5 for LVP and further that I will be able to use the LCD properly. The device I am targeting is the PIC18F2550.

Yes this should be no problem.

[croudyj]

Ben,

Thanks for the quick reply. Do you know what the manual means when it says there is "no point trying"? Did I completely misunderstand what it was saying? As long as I can use the LCD with a PIC18F2550 I'm in business.

Thanks again,

John

[Benj]

Hello John

PPP should always be able to auto detect chips if LVP is disabled or not. I think what the datasheet is saying is this. If you are powering the board from the 5V USB supply and the target PIC device has LVP disabled then it will not be detected or programmed. Since you are going to be using the external supply this should never be a problem.

The onboard LCD will work fine with the 18F2550 device.

[croudyj]

Ben,

Thanks for the clear explanation. I am no longer confused!

John