Baby Pac-man on 7800 using VCS Modern Controller
Entry posted by flickertail
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After some additional hacking on the USB today, I have created a definition for the Atari VCS Modern Controller. So now both the Classic and the Modern controllers work with the 2600/7800.
Here's a link of me playing Baby Pac-man on the 7800 using the Modern controller. I apologize for the video. It's just to demo the fact that it works. It was hard to film one-handed, so I apologize for the controller covering the TV half the time.
USB Packet Payloads
Where as the Classic controller has a 5 byte USB message payload, the Modern controller has a 15 byte payload. Here is how they match up (C) on the Classic, (M) on the Modern
Byte 0 - Header Info
Byte 1 - Fire Button Info
- 0x01 (C) Thumb Button, (M) 'A' Button
- 0x02 (C) Side Button, (M) 'B' Button
- 0x04 (M) 'X' Button
- 0x08 (M) 'Y' Button
- 0x10 (M) 'L' Shoulder Button
- 0x20 (M) 'R' Shoulder Button
- 0x40 (M) 'L' Joystick Button
- 0x80 (M) 'R' Joystick Button
Byte 2 - D-Pad Direction and Function Buttons - Essentially the same on both
- 0x01 (C & M) 'Back' Function Button
- 0x02 (C & M) 'Ham' Function Button (aka Fwd)
- 0x04 (C & M) 'Atari' Function Button
- 0x10 (C & M) D-Pad North
- 0x20 (C & M) D-Pad North East
- 0x30 (C & M) D-Pad East
- 0x40 (C & M) D-Pad South East
- 0x50 (C & M) D-Pad South
- 0x60 (C & M) D-Pad South West
- 0x70 (C & M) D-Pad West
- 0x80 (C & M) D-Pad North West
Bytes 3 & 4
-
Byte 3 (C): 0-255 Unsigned Int
- Used to determine 90 rotation through 1/4 of a circle
- Primary use for emulation of paddle around classic controller central pole
-
Byte 4 (C): 0-3 Unsigned Int
- Used to identify which quadrant of the circle that is currently being used as the base for the paddle rotation
Bytes 3 & 4 (M): 16bit Signed Int
- Used for Left Joystick X-Axis
- Full Left Value: -32,XXX; Center Value: 0; Full Right Value: 32,XXX
Bytes 5 & 6 (M): 16bit Signed Int
- Used for Left Joystick Y-Axis
- Full North Value: -32,XXX; Center Value: 0; Full South Value: 32,XXX
Bytes 7 & 8 (M): 16bit Signed Int
- Used for Right Joystick X-Axis
- Full West Value: -32,XXX; Center Value: 0; Full East Value: 32,XXX
Bytes 9 & 10 (M): 16bit Signed Int
- Used for Right Joystick Y-Axis
- Full North Value: -32,XXX; Center Value: 0; Full South Value: 32,XXX
Bytes 11 & 12 (M): 16bit Unsigned Int
- Used for Left Trigger Axis
- Not Pulled: 0, Full Pull Value: 65,XXX
Bytes 13 & 14 (M): 16bit Unsigned Int
- Used for Right Trigger Axis
- Not Pulled: 0, Full Pull Value: 65,XXX
What About the Paddles?
The paddle won't be difficult to implement. It's just a matter of adding an AD5242 digital pot chip along with two N-Channel MOSFETs. The MOSFETs aren't entirely necessary, but they implement the Paddle Pin 3/4 fire buttons, and will be controlled by the AD5242 chip. This makes coding for the paddles easier on the Pico as only one I2C command to AD5242 will be required, rather than two... one each to the AD5242 chip and the ADG715 chip.
This reduction may help with performance later when implementing 4 x controllers at the same time.
However, I'm not sure how to implement 4 controllers yet, as TinyUSB doesn't support more than 1 level of USB, so utilizing a USB hub is not an option. I think it would be possible to design a custom RP2040 board with additional USB ports, so that may be one way around it - worst case scenario.
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