The default state of TMUXS7614D is address mode. While in address mode the SPI frame
expects the following sequence:
- CS is
pulled low
- Default of 16 SCLK cycles (or
24 SCLK cycles if CRC is enabled), 16-bit command (1 R/W bit, 7 address
bits, followed by an 8-bit data)
- CS is
pulled high
When the first bit of command is a 0 it indicates a write is being performed or
when the first bit is a 1 it indicates a read is being performed. The next 7 bits
following are for the target register address. The target register is determined
during the 8th SCLK cycle. The last 8 bits are written to the targeted register on
the 16th SCLK cycle, or they are ignored when performing a read. While performing a
read the last 8 bits on SDI are ignored since SDO will output the addressed register
state during these last 8 SCLK cycles. During the first eight bits of any command
SPI sends out 8 alignment bits "0x25" on SDO.