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taskit Port-8 – Protocol Description

Port-8 is the command and data encoding format of the taskit gpio.net modules. It transmits commands and data words in three frame sizes (4 / 8 / 16 bit) over an 8-bit-oriented serial bus (TSB) or UART.

1. Introduction

Port-8 is a self-synchronizing, length-encoded protocol, closely modeled on the UTF-8 principle: every frame starts with a lead byte whose leading bits indicate the total length, followed by continuation bytes with the prefix 10.

Application: GPIO control (setting/reading/toggling PADs) and configuration (direction, pull-up/pull-down, notification).

2. Frame Formats

Port-8 defines three frame sizes, identified by the bit pattern of the first byte (lead byte). Continuation bytes always start with 10, analogous to UTF-8.

2.1 Overview Table

Bytes Lead byte pattern Command bits Data bits Frame type
1 0CCCDDDD 3 (C2–C0) 4 4-bit
2 110CCCDD 10DDDDDD 3 (C2–C0) 8 8-bit
4 1110CCCC 10CCDDDD 10DDDDDD 10DDDDDD 6 (C5–C0) 16 16-bit

2.2 Legend

Symbol Meaning
D Data bit (payload)
C Command bit (command code)
0/1 Fixed bit pattern for frame identification

2.3 Bit Layouts

Each cell corresponds to one bit of the byte. The label below each byte shows the byte-bit position (7 = MSB, 0 = LSB).

2.3.1 · 4-bit — 1 byte — 0CCCDDDD

Byte 0:
┌───┬───┬───┬───┬───┬───┬───┬───┐
│  0│ C2│ C1│ C0│ D3│ D2│ D1│ D0│
└───┴───┴───┴───┴───┴───┴───┴───┘
   7   6   5   4   3   2   1   0

3 command bits (C2–C0) → codes 0–7. 4 data bits.

2.3.2 · 8-bit — 2 bytes — 110CCCDD 10DDDDDD

Byte 0:
┌───┬───┬───┬───┬───┬───┬───┬───┐
│  1│  1│  0│ C2│ C1│ C0│ D7│ D6│
└───┴───┴───┴───┴───┴───┴───┴───┘
   7   6   5   4   3   2   1   0

Byte 1:
┌───┬───┬───┬───┬───┬───┬───┬───┐
│  1│  0│ D5│ D4│ D3│ D2│ D1│ D0│
└───┴───┴───┴───┴───┴───┴───┴───┘
   7   6   5   4   3   2   1   0

3 command bits (C2–C0) → codes 0–7. 8 data bits.

2.3.3 · 16-bit — 4 bytes — 1110CCCC 10CCDDDD 10DDDDDD 10DDDDDD

Byte 0:
┌───┬───┬───┬───┬───┬───┬───┬───┐
│  1│  1│  1│  0│ C5│ C4│ C3│ C2│
└───┴───┴───┴───┴───┴───┴───┴───┘
   7   6   5   4   3   2   1   0

Byte 1:
┌───┬───┬───┬───┬───┬───┬───┬───┐
│  1│  0│ C1│ C0│D15│D14│D13│D12│
└───┴───┴───┴───┴───┴───┴───┴───┘
   7   6   5   4   3   2   1   0

Byte 2:
┌───┬───┬───┬───┬───┬───┬───┬───┐
│  1│  0│D11│D10│ D9│ D8│ D7│ D6│
└───┴───┴───┴───┴───┴───┴───┴───┘
   7   6   5   4   3   2   1   0

Byte 3:
┌───┬───┬───┬───┬───┬───┬───┬───┐
│  1│  0│ D5│ D4│ D3│ D2│ D1│ D0│
└───┴───┴───┴───┴───┴───┴───┴───┘
   7   6   5   4   3   2   1   0

6 command bits (C5–C0) → codes 0–63. 16 data bits – no padding needed, the bits add up exactly (4+2 command bits, 4+6+6 data bits).

4 of the 6 command bits (C5–C2) fit into byte 0 (4 bits remain free after the fixed 1110 prefix); the remaining 2 bits (C1 C0) sit at the start of byte 1, right before the data. This gives the 16-bit frame eight times as many command codes as the 4-/8-bit frame (0–63 instead of 0–7).

3. Commands

Code Name Data Description Datasize
0 Write Value PAD Data 4 / 8 / 16 bit
1 Read-Command Read frequencies 4 / 8 / 16 bit
2 Set Output PAD Mask 4 / 8 / 16 bit
3 Clear Output PAD Mask 4 / 8 / 16 bit
4 Toggle Output PAD Mask 4 / 8 / 16 bit
5 Notification PAD no. + level 4 / 8 / 16 bit
6 I2C Read/Write 8-bit mode 4 / 8 / 16 bit
7 Return Code Error / code 4 / 8 / 16 bit
8 Set Direction PAD Mask 16-bit only
9 Clear Direction PAD Mask 16-bit only
10 Set PullEnable PAD Mask 16-bit only
11 Clear PullEnable PAD Mask 16-bit only
12 Set Notification PAD Mask 16-bit only
13 Clear Notification PAD Mask 16-bit only
14 Pull Direction 0/1 per PAD 16-bit only
15 Delay Delay in ms 16-bit only
16 Set LED LED Mask 16-bit only
17 Clear LED LED Mask 16-bit only
18 Toggle LED LED Mask 16-bit only
19 Read – 16-bit only
20 UART Config Write – 16-bit only
21 UART Config Read – 16-bit only
22 I2C Config Write – 16-bit only
23 I2C Config Read – 16-bit only
24 SPI Config Write – TBD 16-bit only
25 SPI Config Read – TBD 16-bit only
26 ADC Config Write – TBD 16-bit only
27 ADC Config Read – TBD 16-bit only
28 DAC Config Write – TBD 16-bit only
29 DAC Config Read – TBD 16-bit only
30 — reserved — – 16-bit only
31 — reserved — – 16-bit only
32 Reset Hardware – 16-bit only
33 Read HW Version – for example "3.01" 2 x 16-bit
34 Read SW Version – for example "3.01" 2 x 16-bit
35 Read MAC - 3 x 16-bit
36 Write Name Index of Name n x 16-bit
37 Read Name Index of Name n x 16-bit
38 — reserved — – 16-bit only
39 — reserved — – 16-bit only
40 — reserved — – 16-bit only
41 — reserved — – 16-bit only
42 — reserved — – 16-bit only
43 — reserved — – 16-bit only
44 — reserved — – 16-bit only
45 — reserved — – 16-bit only
46 — reserved — – 16-bit only
47 — reserved — – 16-bit only
48 — reserved — – 16-bit only
49 — reserved — – 16-bit only
50 — reserved — – 16-bit only
51 — reserved — – 16-bit only
52 — reserved — – 16-bit only
53 — reserved — – 16-bit only
54 — reserved — – 16-bit only
55 — reserved — – 16-bit only
56 — reserved — – 16-bit only
57 — reserved — – 16-bit only
58 — reserved — – 16-bit only
59 — reserved — – 16-bit only
60 — reserved — – 16-bit only
61 — reserved — – 16-bit only
62 — reserved — – 16-bit only
63 — reserved — –  16-bit only

Indexes of Names - 00 reserved - 01 Type of Hardware for example P4-IO-Jacks - 02 Hardware name (user defined) - 03-0F reserved

  • 10 Jack0 name (user defined)
  • 11 Jack0 connected HW
  • 12 Jack0 taskit HW Nr
  • 13-17 reserved
  • 18 Jack0-Pin0 name (user defined)
  • 19 Jack0-Pin1 name (user defined)
  • 1A Jack0-Pin2 name (user defined)
  • 1B Jack0-Pin3 name (user defined)

  • 1C-1F reserved

  • 20 Jack1 name (user defined)

  • 21 Jack1 connected HW
  • 22-27 reserved
  • 28 Jack1-Pin0 name (user defined)
  • 29 Jack1-Pin1 name (user defined)
  • 2A Jack1-Pin2 name (user defined)
  • 2B Jack1-Pin3 name (user defined)

  • 2C-2F reserved

  • 30 Jack2 name (user defined)

  • 31 Jack2 connected HW
  • 32-37 reserved
  • 38 Jack2-Pin0 name (user defined)
  • 39 Jack2-Pin1 name (user defined)
  • 3A Jack2-Pin2 name (user defined)
  • 3B Jack2-Pin3 name (user defined)

  • 3C-1F reserved

  • 40 Jack3 name (user defined)

  • 41 Jack3 connected HW
  • 42-47 reserved
  • 48 Jack3-Pin0 name (user defined)
  • 49 Jack3-Pin1 name (user defined)
  • 4A Jack3-Pin2 name (user defined)
  • 4B Jack3-Pin3 name (user defined)
  • 4C-4F reserved

3.1 Default Names & UI Behavior

  • Names (Hardware, Jack, Pin) are pre-populated with sensible defaults (e.g. Jack0, Jack0-Pin0) rather than left empty — Write Name (36) only needs to be used to override a default.
  • Names are shown directly in the jack view of the configuration UI, next to the corresponding jack/pin — no separate page needed to see them.
  • Names are editable in place within the jack view (inline edit via Write Name (36) / Read Name (37)), not via a separate settings screen.

  • The burger menu contains only Import and Export — naming and other jack settings live in the jack view itself.

  • PAD Mask: bitfield, each set bit addresses one PAD (width = data width of the frame: 4 / 8 / 16 bit).

  • Codes 0–7 fit in 3 bits and are therefore usable in all three frame sizes.
  • Codes 8–63 require more than 3 command bits and are therefore only available in the 16-bit frame (6 command bits, codes 0–63). Codes 16–63 are currently reserved/unassigned.
  • Pull configuration: requires two commands – first Set PullEnable (10), then Pull Direction (14) to select pull-up/pull-down.

4. Cross References