HP97 The journey begins

[teenix]

Hi All,

I had some trouble with the IR print link and none of my efforts would get it to work. I then rewrote the IR code to a more simpler version although it does have a very small amount of bit jitter in the data stream, but this didn't work either. I opened the printer and looked at the output from the IR conditioning IC and the data was being received ok, so the IR LED link was working.

I was reading the printer manual again, and "Derrrr" each print line needs a Line Feed at the end or the data just stays in the print buffer. I added that to the print character string and Woolah!! the IR printer interface now seems to work.

The small amount of jitter doesn't appear to worry the printer.

Woo Hoo (Go away Murphy)

I got out a hair dryer to heat up the 97 CPU board and see if the link fails due to timing changes, but it still printed ok when the board was hot. Perhaps as I mentioned earlier, the corrections applied in the printer firmware create a bit of error margin.

Now the fun part, and maybe the last thing to do, diverting the original 97 print data to the IR link. This I hope won't be too hard, but the 97 print data comes in spurts for each line due to the way the HP Microcode sends the data to the PIK chip, so will see. The difficult part is that the print lines cannot be sent as ASCII codes but will have to be output in graphical format because the IR printer does not support all of the 97 PIK character set.

The IR led is only 3mm round, so if one wants to drill a small hole in the rear bottom of the case, there is a small flat vertical area just below the metal locking tab and is where the 97S cable to the interface would have been.

cheers

Tony