Chameleon hardware V1 vs V2

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Chameleon V2 buttons
Chameleon V2 external connectors
Chameleon infrared detector
Chameleon V2 connected to C64
Chameleon V2 battery holder
Chameleon V2 JTAG connector location

The 2019 version of the Chameleon is called Chameleon V2. It's a major hardware revision mainly due to the old FPGA (Altera type EP3C25) not being available any more at affordable prices. The Cyclone 10 series are now replacing the old Cyclone 3 series, but that's not available as a drop-in replacement. We therefore decided to take the chance and make a few more changes to the hardware that make automated production possible.

If a topic is not listed here, you can safely assume that there is no difference between V1 and V2.


FPGA difference

The main difference between the FPGAs is the package: While V1 used an eQFP144 package, the new Chameleon uses a 256-ball BGA package. The size in terms of logic elements, block ram and PLLs is identical down to the last logic cell and number of memory bits. Under the hood, the main clock of this FPGA is not 8MHz any more, but a separate 50MHz oscillator, which will make operation in high-EMI environments (such as near a mobile phone) more reliable.

external interface circuit

While the V1 hardware used a XC9572XL CPLD to talk to the outside world, the new V2 hardware implements this with discrete 5V-tolerant 3.3V TTL chips. This ensures improved field-serviceability, and these TTL chips are less prone to fail due to a latch-up. External interfaces driven by discrete TTL chips are:

  • PS2 keyboard
  • PS2 mouse
  • IEC
  • Infrared
  • clock port (for RR-Net)
  • LEDs


Chameleon V1 used three identical buttons with blue caps. Customers often complained that they had to "push hard" on these buttons before they react. Further, the identical colours made it difficult to refer to each button in a manual. We therefore changed to a different button type that has a "click" and that can be equipped with different-colour caps.

case and battery holder

The case now has a screw at the bottom, so opening for battery installation is much easier (no more special instructions where to pry first!). The battery holder is now mounted directly on the circuit board (instead of freely-flying on top of other components), which makes it much more stable.

Inside the case, there are more tiny changes: The 8MHz crystal has been moved to a position where it cannot conflict any more with the GAL chip of RR-Net MK3. This lets the case close nicely, without any pushing.

external connectors

PS2 and IEC connectors are now solid mini-DIN connectors with the standard colours for keyboard and mouse. For the IEC connector, we opted for a 7-pin mini-DIN connector in black. A special cable is available for connection to an IEC device such as a floppy drive or printer. This eliminates the old breakout cable.

external power supply

The V1 hardware got it's external power through the breakout cable. The new V2 hardware has a dedicated mini-USB connector as a power input. While there had to be a diode in the breakout cable to make sure that power does not go the wrong way, this protection is purely mechanical on the V2 hardware: If the cartridge is used in the expansion port of a C64, the power-connector is hidden behind the metal shield, inside the C64 where it is not accessible. This eliminates the Schottky diode and therefore reduces the recommended supply voltage: While we recommended a 5.2V supply for the V1 hardware, the new recommendation for the V2 hardware is now 5.0V. If you still have a 5.2V supply, you can still use that, but a rather powerful protection diode inside the Chameleon will burn the excess voltage.

IR detector

The infrared eye of the Chameleon is now in a different mounting position that lets the case hold against any pushing from the outside. This eliminates the need for hot-glue behind the detector, which did not stand much pushing anyway. Further, the new mounting position will catch infrared signals even better, as it's further away from the C64 case.

core development

iComp will continue to support both hardware revisions, because the changes are really minimal, and we don't like the "planned obsolescence" approach of many other computer companies. If you already own the V1 hardware, we don't see a need to buy the V2 hardware.

Core developers will need the new hardware for testing. If you have developed a core for the Chameleon before, please contact us, and we'll work out a good deal for the hew hardware. The new pin files and adapted IO instance are available in Peters github repository.

Core developers will also need a JTAG connection to quickly program the FPGA from the development system. The location of the JTAG connector is different, and if a pin header is installed, RR-Net will not fit the case any more. You may therefore opt to mount the JTAG header on the bottom side of the PCB and modify the JTAG cable, so operation of RR-Net and JTAG at the same time stays possible.

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