
Electrical Specifications
226
December 2003 Revised March 2005
SPRS231D
5.10.2
McBSP as SPI Master or Slave Timing
Table 519 to Table 526 assume testing over recommended operating conditions (see Figure 536 to
Figure 539).
Table 519. McBSP as SPI Master or Slave Timing Requirements (CLKSTP = 10b, CLKXP = 0)
NO.
MASTER
MIN
33.25
SLAVE
MIN
0
UNIT
MAX
MAX
M30
t
su(DRV-CKXL)
t
h(CKXL-DRV)
Setup time, MCBSPx.DR valid before MCBSPx.CLKX low
ns
M31
Hold time, MCBSPx.DR valid after MCBSPx.CLKX low
1
6P + 9
ns
Setup time, MCBSPx.FSX low before
MCBSPx.CLKX high
McBSP1
5
M32
t
su(BFXL-CKXH)
McBSP2
5
ns
McBSP3
6
M33
P =1/(DSPPER_CK or DSPXOR_CK) for McBSP1 and McBSP3, or 1/(ARMPER_CK clock frequency) in nanoseconds (ns) for McBSP2.
For all SPI slave modes, CLKG is programmed as 1/2 of the internal reference clock by setting CLKSM = CLKGDV = 1.
t
c(CKX)
Cycle time, MCBSPx.CLKX
2P
16P
ns
Table 520. McBSP as SPI Master or Slave Switching Characteristics (CLKSTP = 10b, CLKXP = 0)
NO.
PARAMETER
MASTER
MIN
SLAVE
UNIT
MAX
MIN
MAX
M24
t
h(CKXL-FXL)
t
d(FXL-CKXH)
t
d(CKXH-DXV)
Hold time, MCBSPx.FSX low after MCBSPx.CLKX low
§
Delay time, MCBSPx.FSX low to MCBSPx.CLKX high
§#
C 10.5
P + 8.25
ns
M25
2C 10.5
P + 8.25
ns
M26
P =1/(DSPPER_CK or DSPXOR_CK) for McBSP1 and McBSP3, or 1/(ARMPER_CK clock frequency) in nanoseconds (ns) for McBSP2.
For all SPI slave modes, CLKG is programmed as 1/2 of the internal reference clock by setting CLKSM = CLKGDV = 1.
§
T = CLKX period = (1 + CLKGDV) * P
C = CLKX low pulse width = T/2 when CLKGDV is odd or zero and = (CLKGDV/2) * P when CLKGDV is even.
FSRP = FSXP = 1. As a SPI master, MCBSPx.FSX is inverted to provide active-low slave-enable output. As a slave, the active-low signal input
on MCBSPx.FSX and MCBSPx.FSR is inverted before being used internally.
CLKXM = FSXM = 1, CLKRM = FSRM = 0 for master McBSP
CLKXM = CLKRM = FSXM = FSRM = 0 for slave McBSP
#
MCBSPx.FSX must be low before the rising edge of clock to enable slave devices and then begin a SPI transfer at the rising edge of the master
clock (MCBSPx.CLKX).
Delay time, MCBSPx.CLKX high to MCBSPx.DX valid
9.75
10.25
2.75
5P + 34.5
ns
LSB
MSB
M32
M25
M33
M24
M26
M30
M31
Bit 0
Bit 0
Bit (n1)
Bit (n2)
Bit (n3)
Bit (n4)
Bit (n1)
Bit (n2)
Bit (n3)
Bit (n4)
MCBSPx.CLKX
MCBSPx.FSX
MCBSPx.DX_or
_DR_(Master)
MCBSPx.DX_or
_DR_(Slave)
Figure 536. McBSP Timings as SPI Master or Slave: CLKSTP = 10b, CLKXP = 0