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Contents
Overview
Specifications
LogicStart Shield 7 Segment Display
LogicStart Shield VGA
LogicStart Shield Sound
LogicStart Shield Directional Buttons
LogicStart Shield Analog
LogicStart Shield LED’s and Switches
LogicStart Shield Wing Slot
Images
The LogicStart Shield provides everything needed to get started with VHDL and FPGA development on the Papilio with one convenient and easy to connect circuit board.
Learn VHDL with Mike Field's free book written specifically for the Papilio and to be updated for the LogicStart Shield soon.
Dive into the exciting world of customizable Soft Processor's with the ZPUino. Custom peripheral's such as a ZX Spectrum compatible VGA adapter and classic audio chips are just a few of the exciting possibilities. The LogicStart gives you peripherals to experiment with!
Explore the VHDL source code of classic video games such as Pac-Man! The LogicStart's VGA output and Micro-Joystick allow all of the Papilio Arcade games to be synthesized.
Snap off the specially designed VGA Wing along the V-Score groove and you can free up two 8-bit Wing slots!
The 7 Segment Display provides 4 character displays with a dot between each character. It is great for displaying anything from high speed debugging data to a low speed alarm clock.
Name | Direction | Function | Arduino Pin | Papilio Wing Pin | ATmega32U4 Pin | Spartan 6 FPGA Pin |
A | Output | A Segment | D18 | BL3 | P105 | |
B | Output | B Segment | D14 | BL7 | B6 | P115 |
C | Output | C Segment | D16 | BL5 | C7 | P112 |
D | Output | D Segment | D24 | CL1 | P97 | |
E | Output | E Segment | D19 | BL2 | P102 | |
F | Output | F Segment | D17 | BL4 | P111 | |
G | Output | G Segment | D15 | BL6 | C6 | P114 |
DP | Output | Data Point Segment | D22 | CL0 | P99 | |
AN0 | Output | AN0 | D40 | CH1 | P67 | |
AN1 | Output | AN1 | D38 | CH0 | P75 | |
AN2 | Output | AN2 | D34 | CL6 | P81 | |
AN3 | Output | AN3 | D32 | CL5 | P83 | |
AN4 | Output | AN4 | D36 | CL7 | P79 |
The VGA section of the LogicStart Shield uses 12 resistors to implement 4096 color depth. VGA video is analog in nature so there needs to be some way to vary the RGB (Red, Green, and Blue) signals between 0V and .7V. For each RGB signal the shade, or intensity, of the color is controlled by varying the voltage of the pin between 0 and .7V. The finer control you have over the voltage the more colors you can create. For the LogicStart Shield we are able to control 4 Red, 4 Green, and 4 Blue bits which allows us to generate 16 different voltage levels between 0 and .7V for Red and Green and Blue. If we add all three colors together we have 12 bit video which gives us (2^12=4096) the possibility of 4096 colors.
The usual options for controlling voltage on a pin are to use a DAC, PWM, Delta-Sigma, or a resistor ladder. For the LogicStart MegaWing we wanted to use the lowest cost and easiest method for a hobbyist. PWM and Delta-Sigma were ruled out because we did not think we would be able to vary the voltage with these methods fast enough to keep up with the VGA timing requirements. A DAC would be a good solution but was more than we needed for our modest requirements. A resistor ladder fit the bill perfectly because it is very low cost and easy to implement. The resistor ladder is made up of 4r, 4g, 4b resistors that all connect, in common, to the VGA connector on one side and individually to a digital I/O pin on the other side. Each digital I/O pin is controlled by the VGA controller inside the FPGA. Each pin can be set to either 0 or 1 with a 1 causing the resistor to contribute its voltage to the final voltage level. The voltage can be stepped up from 0 to the desired output voltage which in this case is .7V.
Name | Direction | Function | Arduino Pin | Papilio Wing Pin | ATmega32U4 Pin | Spartan 6 FPGA Pin |
Red1 | Output | Red Bit 1 | D23 | DH7 | P98 | |
Red2 | Output | Red Bit 2 | D25 | DH6 | P95 | |
Red3 | Output | Red Bit 3 | D27 | DH5 | P92 | |
Red4 | Output | Red Bit 4 | D29 | DH4 | P87 | |
Green1 | Output | Green Bit 1 | D37 | DH0 | P78 | |
Green2 | Output | Green Bit 2 | D35 | DH1 | P80 | |
Green3 | Output | Green Bit 3 | D33 | DH2 | P82 | |
Green4 | Output | Green Bit 4 | D31 | DH3 | P84 | |
Blue1 | Output | Blue Bit 1 | D49 | DH3 | P51 | |
Blue2 | Output | Blue Bit 2 | D43 | DH5 | P61 | |
Blue3 | Output | Blue Bit 3 | D41 | DH6 | P66 | |
Blue4 | Output | Blue Bit 4 | D39 | DH7 | P74 | |
VSync | Output | Vertical Sync | D51 | DH1 | P48 | |
HSync | Output | Horizontal Sync | D53 | DH0 | P39 |
The sound section implements a 1/8th inch mono jack with a low pass filter. Projects simply implement a Delta-Sigma DAC as outlined in Xilinx App Note 154. A Delta-Sigma DAC allows high quality audio to be implemented with a minimum amount of physical hardware required. The high speed of the FPGA clock allows the FPGA to do the heavy lifting of the Digital to Analog conversion.
Name | Direction | Function | Arduino Pin | Papilio Wing Pin | ATmega32U4 Pin | Spartan 6 FPGA Pin |
Audio-Left | Output | Audio Output Left | D21 | BL0 | P100 | |
Audio-Right | Output | Audio Output Right | D20 | BL1 | P101 |
The LogicStart Shield has 4 momentary switches arranged in a plus configuration that can be used for user input or video games!
Name | Direction | Function | Arduino Pin | Papilio Wing Pin | ATmega32U4 Pin | Spartan 6 FPGA Pin |
Up | Input | Directional Button Up | D11 | B2 | P132 | |
Down | Input | Directional Button Down | D12 | B3 | P133 | |
Left | Input | Directional Button Left | D13 | B1 | P134 | |
Right | Input | Directional Button Right | D10 | B0 | P131 |
The Analog connections allows pots, pot slides, temp sensors, and many more analog devices to be connected, up to 6 devices at once.
The Analog header is connected to the Analog pins of the ATmega32u4 chip on the Papilio DUO.
Name | Direction | Function | Arduino Pin | Papilio Wing Pin | ATmega32U4 Pin | Spartan 6 FPGA Pin |
A0 | Input | Analog Bit 0 | A0 | F0 | ||
A1 | Input | Analog Bit 1 | A1 | F1 | ||
A2 | Input | Analog Bit 2 | A2 | F4 | P81 | |
A3 | Input | Analog Bit 3 | A3 | F5 | P83 | |
A4 | Input | Analog Bit 4 | A4 | F6 | P85 | |
A5 | Input | Analog Bit 5 | A5 | F7 | P88 |
The LogicStart Shield provides 8 LED’s and 8 Slide Switches.
Name | Direction | Function | Arduino Pin | Papilio Wing Pin | ATmega32U4 Pin | Spartan 6 FPGA Pin |
Led0 | Output | Led 0 | D48 | CH5 | P55 | |
Led1 | Output | Led 1 | D50 | CH6 | P50 | |
Led2 | Output | Led 2 | D52 | CH7 | 47 | |
Led3 | Output | Led 3 | D5 | AL5 | D6 | P121 |
Led4 | Output | Led 4 | D6 | AL6 | D4 | P123 |
Led5 | Output | Led 5 | D7 | AL7 | D1 | P124 |
Led6 | Output | Led 6 | D8 | D0 | P126 | |
Led7 | Output | Led 7 | D9 | B7 | P127 | |
SW0 | Input | Switch 0 | D0 | AL0 | D2 | P116 |
SW1 | Input | Switch 1 | D1 | AL1 | D3 | P117 |
SW2 | Input | Switch 2 | D2 | AL2 | B5 | P118 |
SW3 | Input | Switch 3 | D3 | AL3 | B4 | P119 |
SW4 | Input | Switch 4 | D4 | AL4 | D7 | P120 |
SW5 | Input | Switch 5 | D42 | CH2 | P62 | |
SW6 | Input | Switch 6 | D44 | CH3 | P59 | |
SW7 | Input | Switch 7 | D46 | CH4 | P57 |
One of the most often requested features for the original LogicStart MegaWing was the ability to expand it with Wings. We listened and updated the LogicStart Shield with a Wing that shares the Switch pins. The Switches are configured so that when they are in the "Up" position they are not directly connected to 3.3V. Instead they are connected to a weak pullup resistor that "pulls" the voltage up to 3.3V. This weak pullup can be overridden by something connected to the Wing Slot. So in order to use the Wing Slot you will need to insure that all of the switches are in the "Up" position. If they are in the down position they will be connected to ground and the Wing will not be able to override that state.
Name | Direction | Function | Arduino Pin | Papilio Wing Pin | ATmega32U4 Pin | Spartan 6 FPGA Pin |
WING1_7 | INOUT | Switch 0 | D0 | D2 | P116 | |
WING1_6 | INOUT | Switch 1 | D1 | D3 | P117 | |
WING1_5 | INOUT | Switch 2 | D2 | B5 | P118 | |
WING1_4 | INOUT | Switch 3 | D3 | B4 | P119 | |
WING1_3 | INOUT | Switch 4 | D4 | D7 | P120 | |
WING1_2 | INOUT | Switch 5 | D42 | P62 | ||
WING1_1 | INOUT | Switch 6 | D44 | P59 | ||
WING1_0 | INOUT | Switch 7 | D46 | P57 |
LogicStart Shield High Resolution Image
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LogicStart Shield Schematics
Click the image to load a PDF version of the LogicStart Shield Schematics
Papilio DUO Pinouts
Click the image to load a PDF version of Papilio DUO pinouts diagram