DS508UM1
101
6.18
SSI Registers
6.18.1
SYNCIO — Synchronous Serial ADC Interface Data Register
ADDRESS: 0x8000.0500
SYNCIO is a 32-bit read / write register. The data written to the SYNCIO register configures the mas-
ter only SSI. In default mode, the least significant byte is serialized and transmitted out of the synchro-
nous serial interface1 (i.e., SSI1) to configure an external ADC, MSB first. In extended mode, a
variable number of bits are sent from SYNCIO[16-31] as determined by the ADC Configuration
Length. The transfer clock will automatically be started at the programmed frequency and a synchro-
nization pulse will be issued. The ADCIN pin is sampled on every positive going clock edge (or the
falling clock edge, if ADCCKNSEN in SYSCON3 is set) and the result is shifted in to the SYNCIO read
register.
During data transfer, the SSIBUSY bit is set high; at the end of a transfer the SSEOTI interrupt will be
asserted. To clear the interrupt the SYNCIO register must be read. The data read from the SYNCIO
register is the last sixteen bits shifted out of the ADC.
The length of the data frame can be programmed by writing to the SYNCIO register. This allows many
different ADCs to be accommodated. The device is SPI- / Microwire-compatible (transfers are in mul-
tiples of 8 bits). However, to be compatible with some non-SPI / Microwire devices, the data written
to the ADC device can be anything between 8 to 16 bits. This is user-definable per the ADC Config-
uration Extension section of the SYNCIO register.
In the default mode, the bits in SYNCIO have the following meaning:
31-15
14
13
12-8
7-0
Reserved
TXFRMEN
SMCKEN
Frame length
ADC Configuration Byte
In extended mode, the following applies:
15
14
13
12-7 6-0
Reserved
TXFRMEN
SMCKEN
Frame length
ADC Configuration Length
ADC Configuration Extension
NOTE:
The frame length in extended mode is 6 bits wide to allow up to 16 write bits, 1 null bit and 16 read bits
(= 33 cycles).
Summary of Contents for EP7312
Page 8: ...DS508UM1 9 Part I EP7312 User s Manual...
Page 58: ...DS508UM1 59 Part II Pin and Register Reference...
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