RS232 voltage levels from laptop

I am trying to build a programmer, just something simple to load the ICD2 firmware into the PIC16F876A or 877A, whichever I use. My big issue is that I've heard that the JDM design programmers are a no go with laptops due to the low voltages used on laptop serial ports. Not really an issue for me as mine doesn't even have one, just usb. I do have a USB to RS232 adapter, but heard that they are not able to be used either, so I don't know what the solution for me is as I don't have another computer together right now. Anyone have a work around for this?

jaydag71 said:

Anyone have a work around for this?

Click to expand...

I'd be happy to program a device for you with the bootloader code if you're here in the US...

Regards, Mike

Have a look at **broken link removed**. It describes how to make a low voltage cable to program the 876A in order to get a ICD up and working.

Hmmm. I should be able to link to the diagram.
**broken link removed**
and
**broken link removed**

You will also need IC-PROG..
Mike.

no solution as of yet...

Thanks very much for the offer, but I am up in victoria BC, not far, but not the states. I did some reading on the programming specs of the series last night and think that I may be able to use my parallel port to do the same as the serial. Trouble with it is I still have to do some reading on the differences between the two ports. But basically if I can find a copy of the JDM, or something similar that is connected via parallel rather than serial than I may have it? The a copy of software loader that will work through the parallel port. I do have a ton of various loader softwares, but haven't looked through them all as of yet. Sort of hoping that someone out there has already been there and can save me some time? Low voltage programming involves the use of voltage levels that are well within the output capabilities of the adapter (my USB to RS232), as it puts out a max of 8.2V, can someone tell me why then I still cannot use the adapter?? something to do with going into negative voltages?