Clock Stop Mode Timing Diagrams
SPI Operation Using the Clock Stop Mode
6-6
SPRU592E
6.4 Clock Stop Mode Timing Diagrams
The timing diagrams for the four possible clock stop mode configurations are
shown here. Notice that the frame-synchronization signal used in clock stop
mode is active throughout the entire transmission as a slave-enable signal.
Although the timing diagrams show 8-bit transfers, the packet length can be
set to 8, 12, 16, 20, 24, or 32 bits per packet. The receive packet length is
selected with the RWDLEN1 bits of RCR1, and the transmit packet length is
selected with the XWDLEN1 bits of XCR1. For clock stop mode, the values of
RWDLEN1 and XWDLEN1 must be the same because the McBSP transmit
and receive circuits are synchronized to a single clock.
Note:
Even if multiple words are consecutively transferred, the CLKX signal is
always stopped and the FSX signal returns to the inactive state after a packet
transfer. When consecutive packet transfers are performed, this leads to a
minimum idle time of two bit-periods between each packet transfer.
Figure 6
−
2. SPI Transfer With CLKSTP = 10b (no clock delay), CLKXP = 0, CLKRP = 0
Á
Á
Á
Á
Á
Á
Á
Á
B1
B2
B4
B3
B0
B5
B6
B7
B0
B1
B2
B3
B4
B5
B6
B7
FSX/SS
DX or DR/MOSI
(from master)
CLKX/SCK
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
DX or DR/MISO
(from slave)
Notes:
1) If the McBSP is the SPI master (CLKXM = 1), MOSI = DX. If the McBSP is the SPI slave (CLKXM = 0), MOSI = DR.
2) If the McBSP is the SPI master (CLKXM = 1), MISO = DR. If the McBSP is the SPI slave (CLKXM = 0), MISO = DX.
Figure 6
−
3. SPI Transfer With CLKSTP = 11b (clock delay), CLKXP = 0, CLKRP = 1
Á
Á
Á
Á
Á
Á
Á
Á
B1
B2
B4
B3
B0
B5
B6
B7
B0
B1
B2
B3
B4
B5
B6
B7
FSX/SS
DX or DR/MOSI
(from master)
CLKX/SCK
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
DX or DR/MISO
(from slave)
Notes:
1) If the McBSP is the SPI master (CLKXM = 1), MOSI = DX. If the McBSP is the SPI slave (CLKXM = 0), MOSI = DR.
2) If the McBSP is the SPI master (CLKXM = 1), MISO = DR. If the McBSP is the SPI slave (CLKXM = 0), MISO = DX.
Summary of Contents for TMS320VC5509
Page 5: ...vi This page is intentionally left blank ...
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 ...