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Forum Index : Microcontroller and PC projects : VT100 Terminal - Custom Firmware build

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archeocomp
Newbie

Joined: 17/04/2016
Location: Slovakia
Posts: 4

Posted: 06:08am 18 Apr 2016

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Hi. I have assembled the ASCII Video Terminal PCB with 270F256B preprogrammed from Silicon Chip. Works fine. Now I bought a 250F128B, programmed Terminal_V1.3_plus_Bootloader.hex in it with PICKIT3. Works fine. Last step. I installed MPLAB X IDE 3.25, I can build the sources which Geoff published. I had to solve mising plib, but it seems ok now. In dist/default/production directory there is file Terminal.production.hex. If I program this in 250F128B it will not work.

Also there are three different versions of hex. One with bootloader bundled (368kB), another from Geoff's sources download in directory dist/default/production (155kB). If I build sources I get Terminal.production.hex (189kB).

I have been using Netbeans ever since 2001 or so, but I am new to PIC. That makes MPLAB X IDE perfect fit for me. What I would like to do, is to modify the firmware for composite green phosphor CGA monitor, capable of displaying 80 chars per line. At least I will learn something about PIC32 along the way. Can please someone shed some light on build process and different hex sizes?

cosmic frog
Guru

Joined: 09/02/2012
Location: United Kingdom
Posts: 302

Posted: 08:33am 18 Apr 2016

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You can change the colour of the output in hardware just by choosing which connections you use on the RGB connector.
The columns and rows can be changed in software.
There are also some settings you can change by pressing the SHIFT+f12 key.

Dave.Edited by cosmic frog 2016-04-19

Geoffg

Guru

Joined: 06/06/2011
Location: Australia
Posts: 3281

Posted: 12:14pm 18 Apr 2016

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You must use the bootloader to load the HEX file if you build your own version from the source. If you used a PICKit3 you will have overwritten the bootloader and that is why it will not start.

The full version incl bootloader is in the Construction Pack.

Geoff

Geoff Graham - http://geoffg.net

archeocomp
Newbie

Joined: 17/04/2016
Location: Slovakia
Posts: 4

Posted: 08:40am 20 Apr 2016

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Thanks Geoffg. I tried it with bootloader and it works. So far I have only hacked menu a little. Will start with video generation as a next step. Sorry if it is stupid question but why must I use bootloader? It almost seems I bought PicKit3 for no purpose.

Geoffg

Guru

Joined: 06/06/2011
Location: Australia
Posts: 3281

Posted: 10:14am 20 Apr 2016

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To build the firmware plus bootloader version I separately compile the firmware and the bootloader, Then I use a complex and messy method of merging the two hex files into one. Because the merge process is so ad hoc I don't post it on my website.

MPLABX has an easier method of building a combined firmware + bootloader in one operation so if I was doing this again I would try to use that method.

Geoff

Geoff Graham - http://geoffg.net

archeocomp
Newbie

Joined: 17/04/2016
Location: Slovakia
Posts: 4

Posted: 04:41am 24 Apr 2016

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It actually already works. Strange, it was too easy. I am sure some timings are out of specs. But I can now have "almost authentic feeling" CP/M machine with real green phosphor 24 rows x 80 columns VT100 compatible terminal and two 5.25 inch drives (btw). Monitor used is Philips BM7502.

Roman

Edited by archeocomp 2016-04-25

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