SCMD(4) | Device Drivers Manual | SCMD(4)

# NAME

`scmd` — Common driver for the Sparkfun Serial Controlled Motor Driver

# SYNOPSIS

`scmd* at iic? ...`
`scmd* at spi? ...`

# DESCRIPTION

The `scmd` driver provides the common framework to the Sparkfun SCMD board. The SCMD board is a Cypress core ARM SOC in front of a DRV8835 motor driver chip. There are a number of ways to talk to the board and scmdi2c(4) and scmdspi(4) should be consulted for the I2C and SPI frontend drivers. The board is fully documented in the datasheet for at Sparkfun.

The board provides a register address space of 126 registers which control the various behaviors of the motors attached to the board. Each SCMD board can handle two motors, and up to 16 SCMD boards may be chained together allowing for 34 motors to be controlled from a single master instance. The secondary boards are accessed by set of view port registers from the main board. The scmd(4) driver and its associated frontends flatten the main SCMD board and all chained boards into a linear register space that can be opened, seeked, read from and written to like any other file or device without having to worry about the view port.

A command line utility scmdctl(1) is provided that allows convenient command line commands for most of the functions provided by the SCMD board.

# SYSCTL VARIABLES

The following sysctl(3) variables are provided:

`hw.scmd0.debug`
  If the driver is compiled with `SCMD_DEBUG`, this node will appear and can be used to set the debugging level.

# FILES

/dev/scmd u
  character device allowing access to the register space of a main u, SCMD device

# SEE ALSO

iic(4), spi(4), scmdi2c(4), scmdspi(4), scmdctl(1), sysctl(8)

# HISTORY

The `scmd` driver first appeared in NetBSD 10.0.

# AUTHORS

The `scmd` driver was written by Brad Spencer <brad@anduin.eldar.org>.

January 1, 2022 | NetBSD 11.0