Software and Errata for NESRGB Kit



Software Changelog

Version 1.7 - I spent more time on RAM access logic and it should be solid now.

Version 1.7 FBX Palette - Special build with a different palette #1



Buggy Releases

Most boards sold between December 2016 and October 2017 have a fake voltage regulator IC fitted.

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How to identify.

Genuine
Genuine

The genuine part has clear printing and a circular mould marking in the centre of its package, the text depends on manufacture date.
Fake
Fake

The fake part has poor quality printing, no mould marking, the text always reads HU1625 042.

The part number is MCP1703T-3302E/MB manufactured by Microchip. The fake is probably a Chinese LM1117 or similar (eg. AMS1117-3.3).

The fake part is not a direct equivalent for the genuine one. The genuine part is designed for stability with a ceramic output capacitors in the 2-10 uF range. The fake part is probably meant to have an electrolytic or tantalum output capacitor in the 10-100 uF range. In some cases the fake voltage regulator will oscillate. Here's a video of this symptom.

Solution #1

Add an extra electrolytic capacitor between the 3.3V power rail and ground. This should make the fake regulator operate correctly and prevent oscillation. The easiest place to solder the capacitor is on the programming header. The positive leg of the cap should be soldered to pin 1 (encircled)  which is 3.3V, the negative leg soldered to pin 2 which is ground. The capacitor should be either a 22 uF or 47 uF type - any voltage rating will do.

capacitor fix (small)

Solution #2

The second, more difficult solution is to replace the fake voltage regulator with a genuine part. To remove it from the PCB you can use a hot air rework station or a soldering iron. The method for the soldering iron is to add extra solder to each of the three pins, then hold the iron in such a way as the tip is making contact with all three pins simultaneously. The thermal connection between the centre pin and the tab will eventually cause the solder to melt. Then the part will slide off the board.

 






How to update the PLD software

board_jtag.jpg (70923 bytes) JTAG_pinout.png (1608 bytes)

To update the software a JTAG programmer is required. I recommend an Altera USB Blaster or clone.

There is an umarked 6 pin  JTAG programming connection on the lower left hand side of the board. Pin 1 is encircled.

JTAG Pinout

  1. +3.3V power rail
  2. Ground
  3. TDO
  4. TCK
  5. TDI
  6. TMS

The Altera USB Blaster requires the Quartus II Progammer Software for Windows to be installed. The download is 185 MB and installation requires 700 MB of hard disk space. The USB Blaster drivers are included in the package (find them in the folder after installation).

Downloads:
Quartus II Progammer Software for Windows   - Version 13.1 - working on Windows 7 and XP

quartus2prg.png (9626 bytes)

To use:

Last updated 18/10/2017.