Free PDK is an open sourced and independently created tool-chain for the Padauk 8-Bit Microcontrollers, created as an alternative to the proprietary and closed tools provided by the Taiwanese company itself.

This includes the EasyPDKProg µC programmer hardware, adding support for the Padauk µCs to the SDCC C-Compiler, as well as comprehensive documentation of the instruction set architecture, and code examples.

The main focus is on supporting µCs of two Padauk series:

Padauk µCs are extremely inexpensive, priced as low as $0.03/pc in volumes of 100, which is why they generated a lot of interest after being featured by Dave from the EEVblog (first video and a bunch of follow-up videos). Despite the low price, it was found that the Padauk µCs sport an interesting architecture that can be a seen as a significant and meaningful extension of the Microchip PIC architecture. There is an extensive and active discussion on the EEVblog forum for this project and further discussion here on µC.net (German).

This page provides an overview of the different sub-projects created in the free-pdk GitHub organization. It also provides custom pinout diagrams for some of the Padauk µCs.

:link: Easy PDK Programmer

Image of the Programmer

Padauk µCs are programmed via a proprietary high-voltage protocol. The protocol was reverse engineered and a fully open source programmer that already supports almost two dozen Padauk µCs has been created. All sources for the programmer are available at:

:link: Lite Version for Automated Assembly

In addition to the fully featured original Easy PDK programmer, there is also a “lite” version available. This version uses a slightly simplified BOM and selects smaller components that are more suitable for automated assembly. You can upload the design files to JLCPCB and get a mostly assembled programmer delivered to you in weeks. Some parts have to be added manually. It uses the same software as the normal programmer.

:link: SDCC-based Open Source Tool-Chain

Padauk’s own tool-chain is based on a custom programming language called “Mini-C” with a syntax based on the C-language. This language is only supported by their own tool-chain, including IDE (“Padauk Developer Studio”) and programmer (“Writer”). The tool-chain also uses a custom binary format with encryption/obfuscation. Should you be interested in code samples in that custom language, take a look at free-pdk/fppa-code-examples.

The open source tool-chain is based on the Small Device C-Compiler (SDCC) and therefore does support Standard C and common binary output formats (intel hex and bin), including those used by the Easy PDK Programmer.

Please note that right now there is no interchangeability between both tool-chains. Binaries generated by SDCC cannot be written by the official Padauk programmer, but only by the Easy PDK Programmer.

Padauk µCs use different kinds of instruction sets: 13, 14, 15, or 16 bit (more information on these instruction sets can be found below). Support for the 14 and 15 bit Padauk instruction sets has been added to SDCC, a C compiler for small devices. Support for the 13 bit Padauk instruction set is being worked on.

Helpful SDCC resources:

:link: Installing SDCC

The latest binaries and sources of SDCC can be obtained on the SDCC website. If SDCC is available via your operating system’s package manager, please ensure that it is at least SDCC 4.0.0; older versions may not have support or only limited support for the Padauk µC.

:link: µC-specific Information and Pinouts

Note: Other µCs than the µCs listed here may be supported. If you want to learn more about the naming scheme, read more here.

:link: MTP (Flash) Variants

MCU OSS Status Arch. max IO ROM RAM Timers PWM CMP ADC Special Padauk Links
PFS122 Supported
(beta) 		PDK14 14

2 KW

 128 T16
T2 T3		 2x 8‑Bit 1 12‑Bit Product Page
Datasheet
PFS154 Supported PDK14 14

2 KW

 128 T16
T2 T3		 2x 8‑Bit
3x 11‑Bit		 1 ‑ LCD Product Page
Datasheet
PFS172 Supported
Legacy device 		PDK14 14

2 KW

 128 T16
T2 T3		 2x 8‑Bit 1 8‑Bit Product Page
Datasheet
PFS173 Supported
Legacy device 		PDK15 18

3 KW

 256 T16
T2 T3		 2x 8‑Bit
3x 11‑Bit		 1 8‑Bit LCD Product Page
Datasheet

:link: OTP Variants

MCU OSS Status Arch. max IO ROM RAM Timers PWM CMP ADC Special Padauk Links
PMS150C Supported PDK13 6

1 KW

 64 T16
T2		 1x 8‑Bit 1 ‑ - Product Page
Datasheet
PMS15A Supported PDK13 6

0.5 KW
 (1 KW *)

 64 T16
T2		 1x 8‑Bit 1 ‑ - Product Page
Datasheet
PMS152 Supported PDK14 14

1.25 KW

 80 T16
T2		 1x 8‑Bit
3x 11‑Bit		 1 ‑ - Product Page
Datasheet
PMS154C Supported PDK14 14

2 KW

 128 T16
T2 T3		 2x 8‑Bit
3x 11‑Bit		 1 ‑ LCD Product Page
Datasheet
PMS171B Supported PDK14 14

1.5 KW

 96 T16
 T2 T3		 2x 8‑Bit 1 8‑Bit - Product Page
Datasheet

:link: Evaluation Boards

These are evaluation boards for the online-programmable MTP (as opposed to the OTP parts, which can only be programmed offline and once) Padauk µC. free-pdk/f-eval-boards.

:link: Instruction Sets, Opcodes, and Programming Sequence

The different Padauk µCs use either 13, 14, 15, or 16 bit instruction sets. The following files provide an overview over the different instruction sets.

More information, including information on the programming sequence, can be found at free-pdk/fppa-pdk-documentation

:link: Other Tools

  • Schematic Symbols: A collection of schematic symbols for many of the Padauk µCs.
  • Padauk µC Emulator written in VHDL: This project aims to provide a fully functional, timing accurate VHDL model for simulating PADAUK FPPA microcontrollers. free-pdk/fppa-pdk-emulator-vhdl
  • A bunch more tools are located at free-pdk/fppa-pdk-tools.
    • Disassembler: dispdk supports 13 bit, 14 bit, 15 bit and 16 bit opcodes
    • Emulator: emupdk supports 14 bit opcodes, no peripheral support yet requires mapping of processor ID in emucpu.c
    • PDK converter: depdk convert/deobfuscate any PDK file to binary

:link: Projects from the Community

These projects are auto-populated once per day by searching GitHub for repositories with the padauk topic. Projects that additionally have the free-pdk topic are highlighted as Uses Free PDK toolchain. Projects that contain .PRE files are marked as Uses proprietary toolchain.

:link: Latest Activity

The latest activity in the free-pdk GitHub organization is fetched at least once per day and displayed below.

avatar image

@spth commented on issue free-pdk/easy-pdk-programmer-software#94
Supported Devices
How about MF324?

avatar image

@cnlohr commented on issue free-pdk/easy-pdk-programmer-software#85
PFS122B support
ah, sorry, I lost track of this project. I may or may not return to it, but, thank you for the feedback.

avatar image

@cpldcpu commented on issue free-pdk/easy-pdk-programmer-hardware#31
3d printed case
looks great!

avatar image

@argofowl commented on issue free-pdk/fppa-pdk-tools#9
reverse depdk tool
Thanks Johannes, that works. Take the time you need to get the tools set up. Once you post the templates and test program, I'll check them against the converter and we can pin down the first test.

Argo

avatar image

@kibix commented on issue free-pdk/fppa-pdk-tools#9
reverse depdk tool
i will need a couple of days to organise this all, the tools are in a
box since years, need to be set up etc. not priority to do it with
urgency. but it will be done and i will get bach here then with the
required templates etc

Johannes


On 7 Sep 2026, at 23:38, artoshi wrote:

> artoshirei left a comment (free-pdk/fppa-pdk-tools#9)
>
> @kibix Hi Johannes, have you had a chance to arrange the PFS122 test?
> I'd like to get the converter in #10 through that final check with
> you.
>
> My offer is US$50 total via PayPal, payable after your official tools
> accept the output and the chip programs and runs correctly, subject to
> the template/calibration check we discussed.
>
> Would you like to proceed with my offer? If so, please attach the
> non-confidential official .pdk template and matching SDCC test
> program, with the tool versions and calibration details from the
> checklist above. I'll review those first and confirm the scope and
> turnaround before we start.
>
> Argo
>
>
> --
> Reply to this email directly or view it on GitHub:
> https://github.com/free-pdk/fppa-pdk-tools/issues/9#issuecomment-5575865012
> You are receiving this because you were mentioned.
>
> Message ID: ***@***.***>

avatar image

@argofowl commented on issue free-pdk/fppa-pdk-tools#9
reverse depdk tool
@kibix Hi Johannes, have you had a chance to arrange the PFS122 test? I'd like to get the converter in #10 through that final check with you.

My offer is US$50 total via PayPal, payable after your official tools accept the output and the chip programs and runs correctly, subject to the template/calibration check we discussed.

Would you like to proceed with my offer? If so, please attach the non-confidential official .pdk template and matching SDCC test program, with the tool versions and calibration details from the checklist above. I'll review those first and confirm the scope and turnaround before we start.

Argo

avatar image

@cpldcpu commented on issue free-pdk/easy-pdk-programmer-lite-hardware#4
Adaptation with USB-C connector & mounting holes
Great! Indeed, a USB-C update is sorely needed.

avatar image

@zekfer38-netizen commented on issue free-pdk/fppa-pdk-tools#9
reverse depdk tool
Understood — thank you for the clear answer. I withdraw my 75 USDT proposal so there is no ambiguity, and I will not add further messages to this thread. Good luck with the hardware test.