|-F fmt || Specify the printf(3) format to be used for displaying input data. This option is ignored in messages that do not read any input from the SMBus device. The format defaults to 0x%02x for byte input operations, and to 0x%04x for word input operations. For multi-byte input (block read), the same format is used for each individual byte read from the SMBus. |
|-c cmd || This is the value of the command byte to be issued as part of the SMBus message. |
|-f dev || This specifies that dev should be used as the connection to the SMBus, rather than the default of /dev/smb0. |
|-i incnt || An SMBus message should be generated to read incnt bytes from the device. |
|-o outcnt || An SMBus message should be generated to write outcnt bytes to the device. The data values to write are expected to follow all of the options (and their arguments) on the command-line, where the number of data bytes must match the outcnt value. |
|-p || This selects the probe bus modus of operation. |
|-s slave || The slave parameter specifies which SMBus device to connect to. This option also selects the transfer messages from/to device modus of operation, where a slave address is mandatory. |
|-w || This option specifies that IO operations are word operations, rather than byte operations. Either incnt, or outcnt (or both) must be equal 2 in this case. Note that the SMBus byte order is defined to be little-endian (low byte first, high byte follows). |
Not all argument combinations make sense in order to form valid SMBus messages. If no -c cmd option has been provided, the following messages can be issued:
Note in particular that specifying 0 as a count value has a different meaning than omitting the respective option entirely.
Typical usage examples of the smbmsg command include:
"smbmsg -f /dev/smb1 -p"
Probe all devices on the SMBus attached to /dev/smb1.
"smbmsg -s 0x70 -i 1"
Issue a receive byte message to the device at address 0x70, and display the received byte using the default format.
"smbmsg -s 0x70 -c 0xff -i 1 -F %d"
Issue a read byte message to the device at slave address 0x70, using 255 (0xff) as the command-byte to send to the device, and display the result using the custom format %d.
"smbmsg -s 0xa0 -c 0 -o 1 0x80"
Send a write byte message to the slave device at address 0xa0, using 0 as the command-byte value, and 0x80 as the byte to send (after the command). Assuming this might be a Philips PCF8583 real-time clock, this would stop the clock.
"smbmsg -s 0xa0 -c 1 -i 6 -F %02x"
Send a block read command to device at address 0xa0, and read 6 bytes from it, using hexadecimal display. Again, assuming a PCF8583 RTC, this would display the fractions of second, seconds, minutes, hours, year/date, and weekday/month values. Since this RTC uses BCD notation, the actual values displayed were decimal then.
"smbmsg -s 0xa0 -c 2 -o 5 0x00 0x07 0x22 0x16 0x05"
Send a block write command to device at address 0xa0. For the PCF8583 RTC, this would set the clock to Sunday (2004%4)-05-16 22:07:00.
Diagnostic messages issued are supposed to be self-explanatory.
printf(3), sysexits(3), smb(4), smbus(4)
.Rs "The SMBus specification"