Interface for MAPS-010144 digital phase shifter

Description

STM32G0B01 based board for controlling daisy-chained digital phase shifter via SPI-like serial interface. User can interface with the board either by buttons and LEDs on the board or via virtual serial port over USB, communication over serial port is realized using simple TLV protocol. The board is providing bipolar supply for the phase shifters.

Repository contents

• KiCAD - ECAD projects of all desinged PCBs for the project
• python_api - Simple python api for communicating with the controller via serial port
• Src - Firmware source code separated from generated STM32 project
• phase_shifter_measurements - Measuremented scattering parameters of the phase shifter

Firmware

Serial communication

Available commands:

Type	Length [bytes]	Value	Description
0x02	1	command id	Ack
0x10	4	phase shifts (0 - 15)	Set phase
0x11	0	-	Transmit
0x12	1	latch state	Latch state

After each message microcontroller should send ACK message with payload containing command id of original message

Example routine to set new phase delay:

1. 0x12 0x01 0x00 - make sure that latch is set low in order to accept data via serial interface
2. 0x10 0x04 0x04 0x02 0x0f 0x08 - send phase shifts to the controller
3. 0x11 0x00 - transmit phase shifts via SPI to the phase shifters
4. 0x12 0x01 0x01 - set latch to update phase shift
5. 0x12 0x01 0x00 - reset latch

Buttons and LEDs

The board is equiped in 3 tactile buttons and two 4-led displays where each display shows according to the silkscreen description either currently selected phase shifter or phase shift set for the selected phase shifter. Buttons have following functions starting from the left most button:

• On short press transmits current phase shifter configuration over SPI
• On short press cycles through 4 phase shifters, on long press sets all phase shifters to 0
• On short press increments phase delay, on long press set current phase shifter to 0