Inputs and Outputs

The NeuralPlex has a separate Vehicle Interface Processor (VIP) that is responsible for all analog inputs, PWM outputs, VRef, RS232/485, and LIN. It also shares three of the four CAN buses with the SOC, allowing it to send/receive CAN messages during the early boot process. The VIP interfaces with the SOC via a high speed SPI bus, and is used by the SOC to configure the baud rate of each CAN bus to ensure the VIP and SOC do not have conflicting baud rates.

VIP

Included in the rootfs, there is a helper utility to assist in writing SPI commands to the VIP. It can be access via the vip command:

Usage: vip <command> [arguments...]

Supported commands:

  nop                                   # No operation
  ain-read      <channel>               # 0-15
  pwm-enable    <channels>              # bitmask 0x01-0x0F
  pwm-config    <channels> <param> <value>
                                        # bitmask 0x01-0x0F
                                        # param: 0=freq, 1=duty
                                        # value: 0-16777215
  vref-enable   <0|1>                   # 0=disable, 1=enable
  vref-config   <millivolts>            # 0-65535 mV
  can-enable    <channel>               # 0-3
  can-baud      <channel> <baudrate>    # baudrate in bit/s (decimal)
  can-timeout   <channel> <seconds>     # timeout in seconds (decimal)
  rs232-stream  <u32-data>
  rs232-config  <baud_idx> <rs485> <bits> <parity> <stop>
  data-ready
  data-recv
  keep-alive    <0|1>                   # 0=disable, 1=enable
  imx-shutdown  <seconds>               # 0 = immediate
  imx-reboot
  s32k-reset                            # Reset S32K1 MCU

Examples:
  vip ain-read 3              # Read AIN Channel 3
  vip pwm-config 15 1 250     # 50% duty, all 4 channels
  vip vref-config 3300        # 3.3V on VREF
  vip can-baud 1 500000       # CAN1 500k
  vip imx-shutdown 15         # Shutdown IMX in 15 seconds

SPI Bus

You may also manually send SPI commands by using the framework shown below:

SPI Bus Settings

MSB first
SCLK active high
CS active low
Data capture on 1st edge, shift (transmit) on 2nd
100kHz clock speed

SPI Frame Structure

OP Code	Data Packet
1 Byte	4 Bytes
MSB<---	--->LSB

OP Codes

0x00 - SPI_NOP
0x10 - ANALOG_INPUT_READ
0x20 - PWM_ENABLE
0x21 - PWM_CONFIG
0x30 - VREF_ENABLE
0x31 - VREF_CONFIG
0x40 - CAN_ENABLE
0x41 - CAN_BAUD_RATE_CONFIG
0x42 - CAN_TIMEOUT
0x50 - RS232_STREAM
0x51 - RS232_CONFIG
0x60 - DATA_READY_ENCODE
0x61 - DATA_RECEIVE
0x70 - IMX_KEEP_ALIVE
0x71 - IMX_SHUTDOWN
0x72 - IMX_REBOOT
0x73 - S32K_RESET

Messages

Individual messages are outlined in the protocol below. The ID represents the OP Code, Byte 0 represents MSB. Message with ID of 0x1XY represents the response message sent back to the SOC (master) one frame after receiving 0xXY. A full frame of 0’s serves as a NOP to allow the SOC to receive a response without sending more data to the VIP. Response to NOP will also be a frame consisting entirely of 0’s.

# Read analog input (opcode=0x10, channel=0x01)
$ spidev_test -D /dev/spidev0.1 -O -s 100000 -v -S 5 -p "\x10\x01\x00\x00\x00"
# Send NOP command to read the result
$ spidev_test -D /dev/spidev0.1 -O -s 100000 -v -S 5 -p "\x00\x00\x00\x00\x00"

# Enable PWM 1 (opcode=0x20, channel=0x01)
$ spidev_test -D /dev/spidev0.1 -O -s 100000 -v -S 5 -p "\x20\x01\x00\x00\x00"

# Enable PWM 1, 2, 3, and 4 (opcode=0x20, channel=0x0F)
$ spidev_test -D /dev/spidev0.1 -O -s 100000 -v -S 5 -p "\x20\x0F\x00\x00\x00"

# Configure VREF to 10000mV (opcode=0x31, voltage=0x2710)
$ spidev_test -D /dev/spidev0.1 -O -s 100000 -v -S 5 -p "\x31\x27\x10\x00\x00"
# Enable VREF (opcode=0x30, enable=0x01)
$ spidev_test -D /dev/spidev0.1 -O -s 100000 -v -S 5 -p "\x30\x01\x00\x00\x00"

# Configure S32K CAN Baud Rate to 500K (opcode=0x41, channel=0x01, baudrate=0x07A120)
$ spidev_test -D /dev/spidev0.1 -O -s 100000 -v -S 5 -p "\x41\x01\x17\xA1\x20"

# Keep IMX alive when IGN goes low (opcode=0x70, enable=0x01)
$ spidev_test -D /dev/spidev0.1 -O -s 100000 -v -S 5 -p "\x70\x01\x00\x00\x00"

# Shutdown IMX in 10 seconds (opcode=0x71, enable=0x01, seconds=0x0A)
$ spidev_test -D /dev/spidev0.1 -O -s 100000 -v -S 5 -p "\x70\x01\x0A\x00\x00"

SPI Protocol

FormatVersion=5.0 // Do not edit this line!
Title="SOC to VIP SPI Bus Protocol"

{ENUMS}
enum PWM_PARAMETER(0="FREQUENCY", 1="DUTY_CYCLE")
enum PARITY(0="NONE", 1="EVEN", 2="ODD")
enum ADC_RESOLUTION(0="10", 1="11", 2="12")
enum DATA_TYPE(0="NONE", 1="STATUSES", 2="RS232", 3="RS485")

{SENDRECEIVE}

[NOP]
ID=000h

[ANALOG_INPUT_READ]
ID=010h
Var=ADC_CHANNEL unsigned 0,4

[ANALOG_INPUT_CONFIG]
ID=011h
Var=RESOLUTION unsigned 0,2 /e:ADC_RESOLUTION

[PWM_ENABLE]
ID=020h
Var=CHANNELS unsigned 0,4

[PWM_CONFIG]
ID=021h
Var=CHANNELS unsigned 0,4
Var=PWM_PARAMTER unsigned 4,2 /e:PWM_PARAMETER
Var=VALUE unsigned 8,24

[VREF_ENABLE]
ID=030h
Var=ENABLE unsigned 0,1

[VREF_CONFIG]
ID=031h
Var=VALUE unsigned 0,16

[CAN_ENABLE]
ID=040h
Var=CAN_CHANNEL unsigned 0,4

[CAN_BAUD_RATE_CONFIG]
ID=041h
Var=CAN_CHANNEL unsigned 0,4
Var=VALUE unsigned 8,24

[CAN_TIMEOUT]
ID=042h
Var=CAN_CHANNEL unsigned 0,4
Var=CAN_TIMEOUT_S unsigned 8,16 /u:s

[RS232_STREAM]
ID=050h
Var=TX unsigned 0,32

[RS232_CONFIG]
ID=051h
Var=BAUD_RATE unsigned 0,5
Var=RS485_FLAG unsigned 7,1
Var=BITS_PER_CHAR unsigned 8,4
Var=PARITY unsigned 12,3 /e:PARITY
Var=STOP_BITS unsigned 15,1

[DATA_READY_DECODE]
ID=060h

[DATA_RECEIVE]
ID=061h

[IMX_KEEP_ALIVE]
ID=070h
Var=KEEP_ALIVE unsigned 0,1

[IMX_SHUTDOWN]
ID=071h
Var=IMX_SHUTDOWN unsigned 0,1
Var=IMX_SHUTDOWN_DELAY_S unsigned 8,16 /u:s

[IMX_REBOOT]
ID=072h
Var=IMX_REBOOT unsigned 0,1

[S32K_RESET]
ID=073h
Var=S32K_RESET unsigned 0,1

[DATA_READY_DECODE_Response]
ID=160h
Var=DATA_TYPE unsigned 0,2 /e:DATA_TYPE
Var=BYTES unsigned 8,8

[ANALOG_INPUT_READ_Response]
ID=110h
Var=ADC_CHANNEL unsigned 0,4
Var=VALUE unsigned 8,16

[DATA_RECEIVE_Response]
ID=161h
Var=DATA unsigned 0,32