iTTL Nikon Protocol – Metz SCA300 interface – software version 1.001

Metz SCA 3000 interface for Metz45 – Teensy/ARDUINO software version 1.001

This is an update of the software version of the implementation of Nikon protocol to manage Metz 45 CL-4.

This new version solves some bugs and permits to use wireless Godox X1R-N (remote flash side).

Some problem still exists but will not be solved with a new version. I started a new project for 50MZ-5 and will design a new software version running on a more powerfull Teensy board. The software design will be change a little taking into account real time event using Interrupt.

Enhancement done

A0 and B0 acknowledge	The previous version does not assert Data signal low after A0 or B0 frame like Nikon Standard. This must be respected to use Godox X1R-N otherwise stay in init state, do not start i-TTL frame exchange.
Adjust clock period	Bug in the previous version, The clock period was too slow, adjust timing to be at same speed than Nikon Standard
Report manual zoom	Report 35mm manual zoom in A0 frame sent to DSLR
i-TTL active condition changed	Because Godox X1R-N do not request A2 frame, I consider i-TTL activ when sent first A0 frame after receiving B1 frame.
Review ISO adjustment table	Review ISO adjustment table for pre-flash 1 and pre-flash1 duration to permit to use the TCM capability of Godox system: remote flash are TTL mode and Controller emulate Manual flash sending appropriate power level to the TTL flash. Permit to control manually and remotely the 45-CL4 power from 1/128 to 1/1. ( with previous version 1/128 was in fact 1/64 at flash level)
Adjust A0 frame	Identify Godox controller (B1 frame) and set bit 1 of byte 5 to 1 in A0 frame.
Clock signal control	Better control of Clock signal input/output mode. In some condition, Clock was switched as input. Modify to avoid this: now always output.

Godox X1R-N

Permit to remotely control the flash power of 45-CL4. Remote flash must be set in TTL mode and the power is manage manually from Godox X2 controller on the DSLR or from the App.

TTL cannot be selected from controller because this I-TTL adapter does not send pre-flash 1. This is a limitation but not very important: In multi-flash photography, it is better to manage manually the power of each group of flash rather than using TLL and expo correction per channel.

Limitation

(No change) With original 45CL3 or 4 flash gun, due to Thyristor circuit design, TTL is only usable with AEL (FL mode) when flash connected to DSLR hot shoe.

- Pre-flash to memorize the exposure

- Take the picture.

As previous version, only pre-flash 2 activated, No pre-flash 1. Then when using Godox, cannot use AEL because do not send light when pre-flash 1 requested. When using remotely this i-TTL adapter with GODOX, flash power must be controlled manually (or set flash in A or M mode but not very convenient setup).

IGBT is the solution to remove this limitation. Go to my 50 MZ-5 project.

Last version of source code

Arduino software to manage i-TTL protocol and Metz 45 CL-3 or CL-4 flash 45-iTTL_V1.001.ino

Document version