Minimig Board v1.0 schematic

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Revision as of 06:35, 2 August 2007 by Freqmax (talk | contribs) (upd)
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Board schematic for Minimig board v1.0

Audio output

Voltage level: (3.3V/(560ohm + 560ohm + 32ohm))*32 ohm*1000 = 91,7mV
Back EMF issues?

4 bit resistor ladder D/A

Notice the resistor of 560 ohm. May cause inlinear output.

FPGA Xilinx XC3S400-4PQ208C
FPGA core power +1,25V +2,5V using LM1117MP-ADJ
Joystick 0
Joystick 1
Jumper
Keyboard & Mouse connections
MC68000
MC68000 Decoupling
Generation of 4.433619 MHz PAL Video MCLK using 74HC4060 (Ntsc=3.579545MHz)

PATCH needed to get rev 1 board working:

Disconnect net SPI_DOUT from pin 81 of FPGA.
Connect net SPI_DOUT to pin 19 of FPGA (net USER3).
REASON
Pin 81 is an output during FPGA config that blocks SPI to MMC during startup.

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Asynchronous static ram 512 x 16 bit (2 chips)

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SD Card slot
Spare I/O