McBSP as an SPI Slave
SPI Operation Using the Clock Stop Mode
6-14
SPRU592E
Table 6
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4. Bit Values Required to Configure the McBSP as an SPI Slave
Required Bit Setting
Description
CLKSTP = 10b or 11b
The clock stop mode (without or with a clock delay) is
selected.
CLKXP = 0 or 1
The polarity of CLKX as seen on the CLKX pin is positive
(CLKXP = 0) or negative (CLKXP = 1).
CLKRP = 0 or 1
The polarity of CLKR as seen on the CLKR pin is
positive (CLKRP = 0) or negative (CLKRP = 1).
CLKXM = 0
The CLKX pin is an input pin, so that it can be driven by
the SPI master. Because CLKSTP = 10b or 11b, CLKR
is driven internally by CLKX.
SCLKME = 0
CLKSM = 1
The clock generated by the sample rate generator
(CLKG) is derived from the McBSP internal input clock.
(The sample rate generator is used to synchronize the
McBSP logic with the externally-generated master
clock.)
CLKGDV = 1
The sample rate generator divides the McBSP internal
input clock by 2 before generating CLKG.
FSXM = 0
The FSX pin is an input pin, so that it can be driven by
the SPI master.
FSXP = 1
The FSX pin is active low.
XDATDLY = 00b
RDATDLY = 00b
These bits must be 0s for SPI slave operation.
When the McBSP is used as an SPI slave, the master clock and slave-enable
signals are generated externally by a master device. Accordingly, the CLKX
and FSX pins must be configured as inputs. The CLKX pin is internally
connected to the CLKR signal, so that both the transmit and receive circuits
of the McBSP are clocked by the external master clock. The FSX pin is also
internally connected to the FSR signal, and no external signal connections are
required on the CLKR and FSR pins.
Although the CLKX signal is generated externally by the master and is
asynchronous to the McBSP, the sample rate generator of the McBSP must
be enabled for proper SPI slave operation. The sample rate generator should
be programmed to its maximum rate of half the McBSP internal input clock
rate. The internal sample rate clock is then used to synchronize the McBSP
logic to the external master clock and slave-enable signals.
Summary of Contents for TMS320VC5509
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Page 43: ...McBSP Operation 2 20 SPRU592E This page is intentionally left blank ...
Page 105: ...SPI Operation Using the Clock Stop Mode 6 16 SPRU592E This page is intentionally left blank ...
Page 187: ...Transmitter Configuration 8 40 SPRU592E This page is intentionally left blank ...
Page 191: ...General Purpose I O on the McBSP Pins 9 4 SPRU592E This page is intentionally left blank ...
Page 201: ...Emulation Power and Reset Considerations 10 10 SPRU592E ...
Page 207: ...Data Packing Examples 11 6 SPRU592E This page is intentionally left blank ...
Page 273: ...McBSP Register Worksheet 13 14 SPRU592E This page is intentionally left blank ...