September 7, 2019

Convoy S2+ firmware - theory of operation for firmware flashing

The Convoy S2+ is based on the Atmel ATTiny13A microcontroller. This is an 8 bit RISC microcontroller with 1K of flash memory. It comes in an 8 pin package, with pins as follows: 
1 - Reset* (not connected)
2 - PB3 (not connected)
3 - PB4
4 - Ground
5 - PB0/MOSI - connected to ground
6 - PB1/MISO - controls all 7135 devices
7 - PB2/SCK - battery monitor
8 - VCC
The 7135 devices each sink 350 mA. Their "Vdd" pin controls them. When Vdd is pulled high, they sink current. My lights have 8 of these, so if they are turned on all together they sink 2800 mA of current.

Programming requires power, ground, and 4 other signals. Reset must be controlled and pulled low. The other 3 are SPI interface on pins 5,6,7 (MOSI,MISO, and SCK).

NOTE that pin 5 being connected to ground is an issue. This trace will need to be cut before you can flash firmware.

Feedback? Questions? Drop me a line!

Tom's Light Info / tom@mmto.org