PNI MS2100 - Manual (Page 6)

PNI Sensor Corporation 133 Aviation Blvd., Suite 101, Santa Rosa, CA 95403-1084 USA;, Fax: (707) 566-2261
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21-Jan-11 Page 6 of 16-
MS2100
Specifications & Instructions
SPI Port Line Descriptions
MOSI – Master Out Slave In
The data sent to the MS2100. Data is transferred most significant bit first. The MOSI line will
accept data once the SPI is enabled by taking SSNOT low. Valid data must be presented at least
100 nS before the rising edge of the clock, and remain valid for 100 nS after the edge. New data
may be presented to the MOSI pin on the falling edge of SCLK.
SSNOT – Slave Select Line
Selects the MS2100 as the operating slave device. The SSNOT line must be low prior to data
transfer and must stay low during the entire transfer. Once the command byte is received by the
MS2100, and the MS2100 begins to execute the command, the SSNOT line can be deselected
until the next SPI transfer.
SCLK – Serial Clock
Used to synchronize both the data in and out through the MISO and MOSI lines. SCLK is gener-
ated by a master device. SCLK should be 1 MHz or less. The MS2100 is configured to run as a
slave device, making it an input. One byte of data is exchanged over eight clock cycles. Data is
captured by the master device on the rising edge of SCLK. Data is shifted out and presented to
the MS2100 on the MOSI pin on the falling edge of SCLK.
MISO – Master In Slave Out
The data sent from the MS2100 to the master. Data is transferred most significant bit first. The
MISO line is placed in a high impedance state if the slave is not selected (SSNOT = 1).