ATMEGA 644PA (SMD)

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igi79
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ATMEGA 644PA (SMD)

Post by igi79 » Sun Mar 06, 2016 8:07 pm

Hi,
Today I finished my 'own' UzeBox based on Reference design F2 - with some modification - I replaced most of the passives with SMDs and microcontroller with SMD version - AT MEGA 644PA. I just set fuses and wrote Supermario demo from hex file and almost everything worked fine on first try: sound is ok, video is almost ok, gamecontrollers, SD card, except single strange problem:
In video is no green color. :o
Problem is that on pins 22 - PC3 (GREEN0), 23 - PC4 (GREEN1) and 24 - PC4 (GREEN2) is just no-changing high signal. On all other blue and red pins is valid signal (tested on oscilloscope).
I also unsoldered resistors (R8,R9,R10) from green pins to double check that on each individual pin is just high signal. I also tested PC3,PC4,PC5 with simple 'blink' code, that output on these pins is ok.
Green is missing in all demos and games which I had tested yet (all from hex files on wiki).

Any idea what could be the cause of this problem?

CunningFellow
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Re: ATMEGA 644PA (SMD)

Post by CunningFellow » Sun Mar 06, 2016 8:51 pm

PC2 PC3 PC4 and PC5 are the JTAG interface.

You will have JTAG enabled in the fuses and therefore the MCU wont have use of those pins.

You must program the 644 via SPI in this application.

igi79
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Joined: Sun Mar 06, 2016 4:55 pm

Re: ATMEGA 644PA (SMD)

Post by igi79 » Sun Mar 06, 2016 9:41 pm

Exactly! Thank you very much, you've made my day!

UzeBox is done and finally working:
IMG_20160306_213119_HDR.jpg
IMG_20160306_213119_HDR.jpg (347.18 KiB) Viewed 2937 times

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uze6666
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Re: ATMEGA 644PA (SMD)

Post by uze6666 » Mon Mar 07, 2016 5:30 am

Very nice pcb! :D What are those 3 big connector at the front, a full midi interface?

hpglow
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Re: ATMEGA 644PA (SMD)

Post by hpglow » Mon Mar 07, 2016 7:54 pm

Very nice home etched PCB.

igi79
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Re: ATMEGA 644PA (SMD)

Post by igi79 » Mon Mar 07, 2016 9:23 pm

3 big connectors are MIDI and 2 gamepad connectors (DIN6 to avoid accidental plugging to MIDI). It is much easier to make round hole than any other shape. DIN connectors also reminds me the old 8-bit czechoslovakian computers (ZX Spextrum clones) where DIN connectors were used for almost every interface.

UzeBox in cheap ABS project box (PCB was designed to fit into it):
img_20160307_211029_hdr.jpg
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D3thAdd3r
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Re: ATMEGA 644PA (SMD)

Post by D3thAdd3r » Mon Mar 07, 2016 11:46 pm

Good work, looks pro!

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TonyD
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Re: ATMEGA 644PA (SMD)

Post by TonyD » Tue Mar 08, 2016 2:20 pm

Nice.

Where did you get the plastic case from?

igi79
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Joined: Sun Mar 06, 2016 4:55 pm

Re: ATMEGA 644PA (SMD)

Post by igi79 » Tue Mar 08, 2016 2:37 pm

I have it from GME (their main branch is next to my office)
http://www.gmelectronic.com/plastic-enc ... t-p622-944
http://www.soselectronic.com/?str=371&a ... name=-km39

I can also publish PCB sketch, as this box is too small for reference design PCB.

igi79
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Joined: Sun Mar 06, 2016 4:55 pm

Re: ATMEGA 644PA (SMD)

Post by igi79 » Tue Mar 08, 2016 7:46 pm

I've attached PCB sketch in Eagle 7.5.
It is optimized for "home production" = toner transfer (no ground planes as big black areas does some problems when removing transfer paper) and most vias are placed outside of components (for wire vias). Parts which were not in the stock in my favorite shop I left THD instead of SMD (some capacitors. optocoupler and voltage regulators). In addition, there are some features, which I found in this forum - socket for WiFi module ESP8266 (version 1, which I had in my drawer) and SPI RAM, which I actually don't have :) There is extra jumper next to MIDI connector to switch between ESP and MIDI as they share same pin. Before anybody try to reproduce this PCB, please notice that there are some routes between 'legs' of AD725. It works fine for me - I have crisp video with nice colors, but it needs extra care while soldering. And of course the board is double layered, so toner transfer must be done at once for both sides. As I already mentioned it fits into KB 35 ABS project box, where is less than 1mm space above DIN connectors (just luck).
myUZE.png
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Last edited by igi79 on Wed Mar 09, 2016 10:50 am, edited 2 times in total.

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