SCA61T Series
Subject to changes 11/17
www.murata.com Doc. nr. 8261900 Rev.A3
MISO master in slave out SCA61T → µP
SCK serial clock µP → SCA61T
CSB chip select (low active) µP → SCA61T
Each transmission starts with a falling edge of CSB and ends with the rising edge. During
transmission, commands and data are controlled by SCK and CSB according to the following rules:
• commands and data are shifted; MSB first, LSB last
• each output data/status bits are shifted out on the falling edge of SCK (MISO line)
• each bit is sampled on the rising edge of SCK (MOSI line)
• after the device is selected with the falling edge of CSB, an 8-bit command is received. The
command defines the operations to be performed
• the rising edge of CSB ends all data transfer and resets internal counter and command register
• if an invalid command is received, no data is shifted into the chip and the MISO remains in high
impedance state until the falling edge of CSB. This reinitializes the serial communication.
• data transfer to MOSI continues immediately after receiving the command in all cases where
data is to be written to SCA61T’s internal registers
• data transfer out from MISO starts with the falling edge of SCK immediately after the last bit of
the SPI command is sampled in on the rising edge of SCK
• maximum SPI clock frequency is 500kHz
• maximum data transfer speed for RDAX is 5300 samples per sec / channel
The SPI command can be either an individual command or a combination of command and data. In
the case of combined command and data, the input data follows uninterruptedly the SPI command
and the output data is shifted out parallel with the input data.
The SPI interface uses an 8-bit instruction (or command) register. The list of commands is given in
Table below.
Measure mode (normal operation mode after power on)
Read temperature data register
Activate Self test for X-channel
Activate Self test for Y-channel
Read X-channel acceleration
Read Y-channel acceleration
Measure mode (MEAS) is standard operation mode after power-up. During normal operation, the
MEAS command is the exit command from Self test.
Read temperature data register (RWTR) reads temperature data register during normal operation
without effecting the operation. Temperature data register is updated every 150 µs. The load
operation is disabled whenever the CSB signal is low, hence CSB must stay high at least 150 µs
prior the RWTR command in order to guarantee correct data. The data transfer is presented in
Figure below. The data is transferred MSB first. In normal operation, it does not matter what data is
written into temperature data register during the RWTR command and hence writing all zeros is
recommended.
