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Enhanced Queued Analog-to-Digital Converter (EQADC)
MPC5644A Microcontroller Reference Manual, Rev. 6
1144
Freescale Semiconductor
The main elements of the EQADC SSI block are the shift registers. The 26-bit transmit shift register in the
master and 26-bit receive shift register in the slave are linked by the SDO pin. In a similar way, the 26-bit
transmit shift register in the slave and 26-bit receive shift register in the master are linked by the SDI pin.
See
. When a data transmission operation is performed, data in the transmit registers is
serially shifted twenty-six bit positions into the receive registers by the FCK clock from the master; data
is exchanged between the master and the slave. Data in the master transmit shift register in the beginning
of a transmission operation becomes the output data for the slave, and data in the master receive shift
register after a transmission operation is the input data from the slave.
Figure 25-86. Full Duplex Pin Connection
25.6.9.1
EQADC SSI data transmission protocol
shows the timing of an EQADC SSI transmission operation. The main characteristics of this
protocol are:
•
FCK is free running, it does not stop between data transmissions. FCK will be driven low:
— When the serial interface is disabled.
— In stop/debug mode.
— Immediately after reset.
•
Frame size is fixed to 26 bits.
•
MSB bit is always transmitted first.
•
Master drives data on the positive edge of FCK and latches incoming data on the next positive edge
of FCK.
•
Slave drives data on the positive edge of FCK and latches incoming data on the negative edge of
FCK.
Master initiates a data transmission by driving SDS low, and its MSB bit on SDO on the positive edge of
FCK. Once an asserted SDS is detected, the slave shifts its data out, one bit at a time, on every FCK
positive edge. Both the master and the slave drive new data on the serial lines on every FCK positive edge.
This process continues until all the initial 26-bits in the master shift register are moved into the slave shift
MASTER
SLAVE
SDO
SDI
FCK
SDS
Baud Rate
Generator
Transmit Shift Register
Receive Shift Register
Receive Shift Register
Transmit Shift Register
Data Registers
CFIFOs and RFIFOs
Summary of Contents for MPC5644A
Page 2: ...MPC5644A Microcontroller Reference Manual Rev 6 2 Freescale Semiconductor...
Page 24: ...MPC5644A Microcontroller Reference Manual Rev 6 24 Freescale Semiconductor...
Page 26: ...MPC5644A Microcontroller Reference Manual Rev 6 26 Freescale Semiconductor...
Page 52: ...Introduction MPC5644A Microcontroller Reference Manual Rev 6 52 Freescale Semiconductor...
Page 56: ...Memory Map MPC5644A Microcontroller Reference Manual Rev 6 56 Freescale Semiconductor...
Page 1228: ...Decimation Filter MPC5644A Microcontroller Reference Manual Rev 6 1228 Freescale Semiconductor...
Page 1440: ...FlexCAN Module MPC5644A Microcontroller Reference Manual Rev 6 1440 Freescale Semiconductor...