Blackmagicdesign Design 3G-SDI Arduino Shield, Installation And Operation Manual, Page: 52 / 253

52 Developer Information
Developer Information
This section of the manual provides all the details you will need if you want to write custom
libraries and develop your own hardware for your Blackmagic 3G-SDI Arduino Shield.
Physical Encoding - I
2
C
The shield operates at the following I
2
C speeds:
1. Standard mode (100 kbit/s)
2. Full speed (400 kbit/s)
The default 7-bit shield I
2
C slave address is 0x6E.
Shield Pin | Function
--------------------- |-----------------------------
A4
| Serial Data (SDA)
A5 | Serial Clock (SCL)
**I
2
C Protocol (Writes):**
(START W) [REG ADDR L] [REG ADDR H] [VAL] [VAL] [VAL] ... (STOP)
**I
2
C Protocol (Reads):**
(START W) [REG ADDR L] [REG ADDR H] ... (STOP) (START R) [VAL] [VAL] [VAL] ... (STOP)
The maximum payload (shown as **VAL** in the examples above) read/write length (following
the internal register address) in a single transaction is 255 bytes.
Physical Encoding - UART
The shield operates with a UART baud rate of 115200, 8-N-1 format.
Shield Pin | Function
--------------------- |-----------------------------
IO1
| Serial Transmit (TX)
IO0 | Serial Receive (RX)
**UART Protocol (Writes):**
[0xDC] [0x42] [REG ADDR L] [REG ADDR H] [‘W’] [LENGTH] [0x00] [VAL] [VAL] [VAL] ...
**UART Protocol (Reads):**
[0xDC] [0x42] [REG ADDR L] [REG ADDR H] [‘R’] [LENGTH] [0x00] [VAL] [VAL] [VAL] ...
The maximum payload (shown as **VAL** in the examples above) read/write length (specified in
the **LENGTH** field) in a single transaction is 255 bytes.
Register Address Map
The shield has the following user address register map:
Address | Name | R/W | Register Description
--------------------- |----------- |----- |-------------------------------
0x0000 - 0x0003 | IDENTITY | R | Hardware Identifier
0x0004 - 0x0005 | HWVERSION | R | Hardware Version
0x0006 - 0x0007 | FWVERSION | R | Firmware Version
| | |
0x1000 | CONTROL | R/W | System Control
| | |
0x2000 | OCARM | R/W | SDI Control Override Arm
0x2001 | OCLENGTH | R/W | SDI Control Override Length