This document describes the SCPI command interface implemented in commands_spi.c for SPI (Serial Peripheral Interface) control on the Melexis IO STM32 platform.

Overview

The commands_spi.c file provides SCPI-like commands for initializing, configuring, and performing data transfers over two SPI peripherals (SPI1 and SPI2). It also supports Vdd control, buffer direction, and chip select (CS) management for flexible SPI communication.

Supported Commands

Vdd Control

Command Pattern	Description
`:VDD?`	Return Vdd state
`:VDD:OFF`	Disable Vdd
`:VDD:3V3`	Set SPI Vdd to 3.3V
`:VDD:5V`	Set SPI Vdd from USB Vbus (5V)

Buffer Direction

Command Pattern	Description
`:SPI:BUFfer`	Set buffer controls DIR_0...DIR_5

SPI1 (Connector X2)

Command Pattern	Description
`:SPI:INFO?`	Get SPI1 settings
`:SPI:Init`	Initialize SPI1 (0-CS0, 1-CS1, 2-Both, 3-None)
`:SPI:DeInit`	Deinitialize SPI1
`:SPI:FRame`	Set frame format (0-Motorola, 1-TI)
`:SPI:DATAsize`	Set data size (0-8bit, 1-16bit)
`:SPI:FirstBit`	Set first bit (0-MSB, 1-LSB)
`:SPI:CPOL`	Set clock polarity (0-Low, 1-High)
`:SPI:CPHA`	Set clock phase (0-1 edge, 1-2 edge)
`:SPI:PRESCaler`	Set prescaler (2, 4, ..., 256)
`:SPI:CS0`	Set CS0
`:SPI:CS0?`	Get CS0
`:SPI:CS1`	Set CS1
`:SPI:CS1?`	Get CS1
`:SPI:ReaD`	Read SPI1 «count 1-256»
`:SPI:WRite`	Write SPI1 «data»[,«data»...256]
`:SPI:WriteReaD`	Write/Read SPI1 «data»[,«data»...256]
`:SPI:EXCHange`	Write/Read SPI1 «count 1-256»,«data»[,«data»...]
`:SPI:0:ReaD`	Read SPI1 slave 0 «count 1-256»
`:SPI:0:WRite`	Write SPI1 slave 0 «data»[,«data»...256]
`:SPI:0:WriteReaD`	Write/Read SPI1 slave 0 «data»[,«data»...256]
`:SPI:0:EXChange`	Write/Read SPI1 slave 0 «count»,«data»[,...]
`:SPI:1:ReaD`	Read SPI1 slave 1 «count 1-256»
`:SPI:1:WRite`	Write SPI1 slave 1 «data»[,«data»...256]
`:SPI:1:WriteReaD`	Write/Read SPI1 slave 1 «data»[,«data»...256]
`:SPI:1:EXCHange`	Write/Read SPI1 slave 1 «count»,«data»[,...]

SPI2 (Header H5)

Command Pattern	Description
`:SPI2:INFO?`	Get SPI2 settings
`:SPI2:Init`	Initialize SPI2 (0-CS0, 1-CS1, 2-Both)
`:SPI2:DeInit`	Deinitialize SPI2
`:SPI2:FRame`	Set frame format (0-Motorola, 1-TI)
`:SPI2:DATAsize`	Set data size (0-8bit, 1-16bit)
`:SPI2:FirstBit`	Set first bit (0-MSB, 1-LSB)
`:SPI2:CPOL`	Set clock polarity (0-Low, 1-High)
`:SPI2:CPHA`	Set clock phase (0-1 edge, 1-2 edge)
`:SPI2:PRESCaler`	Set prescaler (2, 4, ..., 256)
`:SPI2:CS0`	Set CS0
`:SPI2:CS0?`	Get CS0
`:SPI2:CS1`	Set CS1
`:SPI2:CS1?`	Get CS1
`:SPI2:ReaD`	Read SPI2 «count 1-256»
`:SPI2:WRite`	Write SPI2 «data»[,«data»...256]
`:SPI2:WriteReaD`	Write/Read SPI2 «data»[,«data»...256]
`:SPI2:EXCHange`	Write/Read SPI2 «count 1-256»,«data»[,«data»...]
`:SPI2:0:ReaD`	Read SPI2 slave 0 «count 1-256»
`:SPI2:0:WRite`	Write SPI2 slave 0 «data»[,«data»...256]
`:SPI2:0:WriteReaD`	Write/Read SPI2 slave 0 «count»,«data»[,...]
`:SPI2:0:EXCHange`	Write/Read SPI2 slave 0 «count»,«data»[,...]
`:SPI2:1:ReaD`	Read SPI2 slave 1 «count 1-256»
`:SPI2:1:WRite`	Write SPI2 slave 1 «data»[,«data»...256]
`:SPI2:1:WriteReaD`	Write/Read SPI2 slave 1 «data»[,«data»...256]
`:SPI2:1:EXCHange`	Write/Read SPI2 slave 1 «count»,«data»[,...]

Command Details

Vdd Control: Manage SPI Vdd power (OFF, 3.3V, 5V, query state).
Buffer: Set direction of buffer pins DIR_1 to DIR_5.
Init/DeInit: Initialize or deinitialize SPI peripherals and chip select pins.
Frame/DataSize/FirstBit/CPOL/CPHA/Prescaler: Configure SPI frame format, data size, bit order, clock polarity/phase, and baudrate.
CS/CS?: Set or query chip select (CS0/CS1) state or mapping.
ReaD/WRite/WriteReaD/EXCHange: Perform SPI data transfers (read, write, write/read, exchange) with optional slave selection.

Examples

Initialize SPI1

Command sent:

:SPI:Init 0\n

Response:

(OK)>

Set SPI1 Prescaler

Command sent:

:SPI:PRESCaler 8\n

Response:

(OK)>

Write Data to SPI1

Command sent:

:SPI:WRite 12,34,56\n

Response:

(OK)>

Read Data from SPI1

Command sent:

:SPI:ReaD 3\n

Response:

Data: 12 34 56

(OK)>

Exchange Data with SPI1 Slave 0

Command sent:

:SPI:0:EXChange 2,AB,CD\n

Response:

Data: EF 01

(OK)>

Error Example (Invalid Prescaler)

Command sent:

:SPI:PRESCaler 3\n

Response:

ERR: invalid prescaler value

(Some error)>

Notes

Commands are case-insensitive.
The command interface is extensible; new features or pins can be added by updating the command table and implementing the corresponding handler logic.
Some commands require specific hardware features or configurations.