In Circuit EPROM emulator and debugger

Using, learning, programming and modding the Gigatron and anything related.
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gesari
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Joined: 11 Apr 2019, 07:15
Location: Valladolid, Spain
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Re: In Circuit EPROM emulator and debugger

Post by gesari »

First excuse me for my long time out of the forum.
I'm not planning to sell any kit for the ROM emulator, but the layout files are freely available and there are many prototype makers around for the PCB (I ordered the boards to www.pcbway.com).

The components are SMD and they may look difficult to solder, but this is easily done with a fine-point iron solder and a magnifying microscope. The trick for the fine-pitch components is not to apply any solder. Just paint the footprint with a flux pencil, place the component over it, and then apply heat to its pins. There is tin on the pins and the PCB already, and this tin is enough for soldering the pin to the PCB.

The firmware is also freely available.(And surely it can be improved :)

Best Regards
kerouanton
Posts: 20
Joined: 27 Jun 2018, 18:40

Re: In Circuit EPROM emulator and debugger

Post by kerouanton »

Thank you for this nice project. I'm pretty sure your BOM will be shortly part of my next Mouser order!
frob
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Joined: 19 May 2020, 12:50
Location: Canada
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Re: In Circuit EPROM emulator and debugger

Post by frob »

This is a fantastic addition for the Gigatron. well done! I am just ordering my Gigatron kit and already was scheming to do something similar.
I'd like to modify your design a little to use a different RAM device: i found a non-volatile SRAM, which once programmed can be used stand-alone like the original EPROM, so it would be detachable from the emulator/debugger board.
I'm curious what CAD software you used, and if you'd be willing to share the source file ?
I do a lot of SMD prototypes and for that i generally like to design and order a small stainless stencil along with my boards, it makes assembly and soldering a lot quicker with less bridging etc. for that to work well its best to tweak the aperture design a little and generate that from the source along with the gerbers.

Thanks
Frantz
Hans61
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Joined: 29 Dec 2020, 16:15
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Re: In Circuit EPROM emulator and debugger

Post by Hans61 »

Is there still contact with the author? I haven't been able to find anything since the end of this thread.

Unfortunately, when I first saw this project, the LPC1114 was not available anywhere. I came back here by accident and found that you can now buy the LPC1114.

I recreated it and think it's very nice. I uploaded the firmware with FlashMagic and on the FT232R I had to connect pin 26 to GND so that the chip is recognized (the solder bridge is not an accident).
gigatron-rom-emulator.jpg
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axelb
Posts: 41
Joined: 07 Jan 2021, 06:27

Re: In Circuit EPROM emulator and debugger

Post by axelb »

Excellent soldering work! Did you use a reflow oven for this?
How long does it take to load the ROM contents with the serial interface?
Hans61
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Re: In Circuit EPROM emulator and debugger

Post by Hans61 »

I soldered it by hand. I also have a reflow oven (T-962). However, this is only worthwhile for larger quantities. With the stencil, the PCB then also becomes significantly more expensive.
Hand soldering also has the advantage that you can test subassemblies.
I used the oven when building the extension-compact, also to gain experience.

So far I have only used loading from the SD card. Unfortunately, a quick attempt with XMODEM failed. I had tested it with Tera Term. I have to try again calmly.

SD card is very fast. I can try to measure the time next time.
Hans61
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Re: In Circuit EPROM emulator and debugger

Post by Hans61 »

I have just tested it again. Loading the ROM via SD card takes about one second.
I couldn't get it to work with Tera Term via XMODEM. With HyperTerminal it loads the ROM in 47 seconds.

Loading and running gt1 files via SD card or XMODEM also works very well.

If there is a file ROM.BIN on the SD card it will be loaded and started automatically on power on.
Unfortunately it only works with a connected USB cable. Without it goes into debug mode after a short time.
There you have to look at the firmware again, so that it can replace the ROM even without a connected PC.
axelb
Posts: 41
Joined: 07 Jan 2021, 06:27

Re: In Circuit EPROM emulator and debugger

Post by axelb »

Loading from SD card in just one second sounds great! Did you use the original Gerber files posted above or are there any other changes than grounding pin 26 of the FT232R?
Hans61
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Re: In Circuit EPROM emulator and debugger

Post by Hans61 »

I only have the original files from this thread. Except for connecting pin 26 of the FDI with GND I have not changed anything.
Hans61
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Re: In Circuit EPROM emulator and debugger

Post by Hans61 »

I soldered all 5 boards from JLCPCB. All of them worked.
I tried to write down my experience here: https://github.com/hans61/Gigatron-TTL/ ... OMemulator
I still have two left. I can give the piece for 20€ plus shipping from Germany if there is interest.
isd.jpg
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