PRELIMINARY
SF104-P01
SF3013M Fingerprint Image Sensor Module User Manual
Page - 11
3.4 SPI command protocol
Command and data are exchanged throught the SPI MISO and MOSI wires. Each byte
of data sent through the MOSI port brings back a received byte through the MISO port.
Commands can be cascaded one by another. The term “SPI command sequence” in
the following context is defined as a sequence of command code and data bytes exchange
within one active SPISEL strobe.
An SF104 command code may or may not have associated data. The “start” and “srst”
commands don’t have associated data, and take effect immediately after the command code
is sent.
For read/write data commands, the second byte will be the beginning of data byte or
bytes, as illustrated below:
read
command
write
command
Writing and reading a series of register content may look different. For writing to
consecutive registers, an internal address counter is incremented automatically after each
byte written. This design eliminates the need to repeat sending the 0x40+N command for
each byte. So the sequence of read/write commands may look like the following.
