Features
- Purchased FPGA Card
- 1MB SRAM
- 6 bit video on VGA
- PS/2 connector
- FTDI USB to serial converter
- SD or SDHC Card
- 2x3 Header
Connectors
U7
U8
H1 - Power
H2 - I/O Power Source
- 1-2 = FPGA Power
- 2-3 = On-board Regulator
J2 - PS/2 Keyboard
P2 - PS/2 Keyboard
P3 - USB-C
P4 - SD Card
Summing Resistor DAC
- 5% resistors are "good enough"
- Goal is 1V into 75 Ohm VGA load
- 3.3V drive
- FPGA has 8 mA drive
- Using 8 mA (max)
- R4 330 Ohm= 0.8 mA to -8.3 mA
- R3 680 Ohm = 0.8 mA to -4.4 mA
- Output in 4 steps
Voltage Steps
Current Steps (R4)
Schematic
Pin List
set_location_assignment PIN_T2 -to i_CLOCK_50
set_location_assignment PIN_W13 -to n_reset
set_instance_assignment -name WEAK_PULL_UP_RESISTOR ON -to n_reset
set_location_assignment PIN_R1 -to ps2Clk
set_instance_assignment -name WEAK_PULL_UP_RESISTOR ON -to ps2Clk
set_location_assignment PIN_R2 -to ps2Data
set_instance_assignment -name WEAK_PULL_UP_RESISTOR ON -to ps2Data
set_location_assignment PIN_C22 -to serSelect
set_instance_assignment -name WEAK_PULL_UP_RESISTOR ON -to serSelect
set_location_assignment PIN_A10 -to cts1
set_instance_assignment -name WEAK_PULL_UP_RESISTOR ON -to cts1
set_location_assignment PIN_A13 -to rts1
set_location_assignment PIN_B10 -to rxd1
set_instance_assignment -name WEAK_PULL_UP_RESISTOR ON -to rxd1
set_location_assignment PIN_B13 -to txd1
set_location_assignment PIN_B17 -to videoB0
set_location_assignment PIN_A17 -to videoB1
set_location_assignment PIN_B16 -to videoG0
set_location_assignment PIN_A16 -to videoG1
set_location_assignment PIN_B20 -to videoR0
set_location_assignment PIN_A15 -to videoR1
set_location_assignment PIN_B18 -to hSync
set_location_assignment PIN_A18 -to vSync
set_location_assignment PIN_F1 -to n_sRamCS
set_location_assignment PIN_B4 -to n_sRamWE
set_location_assignment PIN_J2 -to n_sRamOE
set_location_assignment PIN_E1 -to sramData[0]
set_location_assignment PIN_C1 -to sramData[1]
set_location_assignment PIN_B1 -to sramData[2]
set_location_assignment PIN_B3 -to sramData[3]
set_location_assignment PIN_B2 -to sramData[4]
set_location_assignment PIN_C2 -to sramData[5]
set_location_assignment PIN_D2 -to sramData[6]
set_location_assignment PIN_F2 -to sramData[7]
set_location_assignment PIN_H1 -to sramAddress[0]
set_location_assignment PIN_J1 -to sramAddress[1]
set_location_assignment PIN_M1 -to sramAddress[2]
set_location_assignment PIN_N1 -to sramAddress[3]
set_location_assignment PIN_A8 -to sramAddress[15]
set_location_assignment PIN_A7 -to sramAddress[14]
set_location_assignment PIN_A6 -to sramAddress[13]
set_location_assignment PIN_A5 -to sramAddress[12]
set_location_assignment PIN_C3 -to sramAddress[11]
set_location_assignment PIN_A4 -to sramAddress[10]
set_location_assignment PIN_A3 -to sramAddress[9]
set_location_assignment PIN_H2 -to sramAddress[8]
set_location_assignment PIN_M2 -to sramAddress[7]
set_location_assignment PIN_N2 -to sramAddress[6]
set_location_assignment PIN_P2 -to sramAddress[5]
set_location_assignment PIN_P1 -to sramAddress[4]
set_location_assignment PIN_B5 -to sramAddress[18]
set_location_assignment PIN_B6 -to sramAddress[17]
set_location_assignment PIN_B7 -to sramAddress[16]
# SDRAM
set_location_assignment PIN_Y6 -to sdRamClk
set_location_assignment PIN_W6 -to sdRamClkEn
set_location_assignment PIN_AA4 -to n_sdRamCas
set_location_assignment PIN_AA3 -to n_sdRamCe
set_location_assignment PIN_AB3 -to n_sdRamRas
set_location_assignment PIN_AB4 -to n_sdRamWe
set_location_assignment PIN_V2 -to sdRamAddr[0]
set_location_assignment PIN_V1 -to sdRamAddr[1]
set_location_assignment PIN_U2 -to sdRamAddr[2]
set_location_assignment PIN_U1 -to sdRamAddr[3]
set_location_assignment PIN_V3 -to sdRamAddr[4]
set_location_assignment PIN_V4 -to sdRamAddr[5]
set_location_assignment PIN_Y2 -to sdRamAddr[6]
set_location_assignment PIN_AA1 -to sdRamAddr[7]
set_location_assignment PIN_Y3 -to sdRamAddr[8]
set_location_assignment PIN_V5 -to sdRamAddr[9]
set_location_assignment PIN_W1 -to sdRamAddr[10]
set_location_assignment PIN_Y4 -to sdRamAddr[11]
set_location_assignment PIN_V6 -to sdRamAddr[12]
set_location_assignment PIN_Y1 -to sdRamAddr[13]
set_location_assignment PIN_W2 -to sdRamAddr[14]
set_location_assignment PIN_AA10 -to sdRamData[0]
set_location_assignment PIN_AB9 -to sdRamData[1]
set_location_assignment PIN_AA9 -to sdRamData[2]
set_location_assignment PIN_AB8 -to sdRamData[3]
set_location_assignment PIN_AA8 -to sdRamData[4]
set_location_assignment PIN_AB7 -to sdRamData[5]
set_location_assignment PIN_AA7 -to sdRamData[6]
set_location_assignment PIN_AB5 -to sdRamData[7]
set_location_assignment PIN_Y7 -to sdRamData[8]
set_location_assignment PIN_W8 -to sdRamData[9]
set_location_assignment PIN_Y8 -to sdRamData[10]
set_location_assignment PIN_V9 -to sdRamData[11]
set_location_assignment PIN_V10 -to sdRamData[12]
set_location_assignment PIN_Y10 -to sdRamData[13]
set_location_assignment PIN_W10 -to sdRamData[14]
set_location_assignment PIN_V11 -to sdRamData[15]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to hSync
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to n_reset
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to ps2Clk
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to ps2Data
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to videoB0
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to videoB1
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to videoG0
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to videoG1
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to videoR0
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to videoR1
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to vSync
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to rts1
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to rxd1
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to txd1
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to n_sRamCS
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to n_sRamOE
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to n_sRamWE
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramData[0]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramData[1]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramData[2]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramData[3]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramData[4]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramData[5]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramData[6]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramData[7]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramAddress[0]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramAddress[1]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramAddress[2]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramAddress[3]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramAddress[4]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramAddress[5]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramAddress[6]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramAddress[7]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramAddress[8]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramAddress[15]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramAddress[14]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramAddress[13]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramAddress[10]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramAddress[9]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramAddress[11]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramAddress[12]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramAddress[16]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramAddress[17]
set_instance_assignment -name IO_STANDARD "3.3-V LVTTL" -to sramAddress[18]
Multicomp Builds
Checkout
Rev 1 Issues
- Wrong DB15HD footprint
- Change to right footprint ib Rev 2
- USB-C too hard to hand solder
- Changing to USB-B Micro ib Rev 2
- Add 5V header ib Rev 2
Rev 1 Prototype
- VGA connector footprint problem
- Using the J1 connector to VGAX49 card
Signal
|
VGAX49 Pin
|
RETRO Pin
|
FPGA Pin
|
R4
|
J1-1
|
J1-47
|
C21
|
R3
|
J1-2
|
J1-48
|
C22
|
G5
|
J1-6
|
J1-45
|
D21
|
G4
|
J1-7
|
J1-46
|
D22
|
B4
|
J1-12
|
J1-43
|
E21
|
B3
|
J1-13
|
J1-44
|
E22
|
HS
|
J1-17
|
J1-41
|
F21
|
VS
|
J1-18
|
J1-42
|
F22
|
Testing with Multicomp
# Video
set_location_assignment PIN_C22 -to videoR0
set_location_assignment PIN_C21 -to videoR1
set_location_assignment PIN_D22 -to videoG0
set_location_assignment PIN_D21 -to videoG1
set_location_assignment PIN_E22 -to videoB0
set_location_assignment PIN_E21 -to videoB1
set_location_assignment PIN_F21 -to hSync
set_location_assignment PIN_F22 -to vSync
# PS/2
set_location_assignment PIN_R1 -to ps2Clk
set_instance_assignment -name WEAK_PULL_UP_RESISTOR ON -to ps2Clk
set_location_assignment PIN_R2 -to ps2Data
set_instance_assignment -name WEAK_PULL_UP_RESISTOR ON -to ps2Data
Assembly Sheet