ꢀ ꢁ ꢂ ꢃ ꢄꢅ ꢆ ꢇ ꢈꢉ ꢈꢀꢊ ꢀꢁ ꢂꢃ ꢄ ꢅ ꢆꢇ ꢈ ꢉ ꢋꢀꢊ ꢀꢁ ꢂꢃ ꢄ ꢅ ꢆꢇ ꢈ ꢉ ꢇ ꢀ
ꢌ ꢍ ꢎꢏ ꢐꢑꢒ ꢓꢍ ꢔ ꢀ ꢐꢍ ꢕ ꢍ ꢀꢖꢗ ꢂ ꢍ ꢕꢔ ꢖꢗ ꢒ ꢘꢓ ꢆꢏ ꢂꢂꢓ ꢘꢂ
SPRS226H − NOVEMBER 2003 − REVISED AUGUST 2005
MULTICHANNEL BUFFERED SERIAL PORT (McBSP) TIMING (CONTINUED)
†‡
timing requirements for McBSP as SPI Master or Slave: CLKSTP = 11b, CLKXP = 1 (see Figure 56)
−600
−720
−850
NO.
UNIT
−1G
MASTER
SLAVE
MIN MAX
MIN
12
4
MAX
4
5
t
t
Setup time, DR valid before CLKX high
Hold time, DR valid after CLKX high
2 − 12P
5 + 24P
ns
ns
su(DRV-CKXH)
h(CKXH-DRV)
†
‡
P = 1/CPU clock frequency in ns. For example, when running parts at 720 MHz, use P = 1.39 ns.
For all SPI Slave modes, CLKG is programmed as 1/4 of the CPU clock by setting CLKSM = CLKGDV = 1.
switching characteristics over recommended operating conditions for McBSP as SPI Master or
†‡
Slave: CLKSTP = 11b, CLKXP = 1 (see Figure 56)
−600
−720
−850
NO.
PARAMETER
UNIT
−1G
§
MASTER
SLAVE
MIN
MIN MAX
MAX
¶
1
2
3
t
t
t
Hold time, FSX low after CLKX high
H − 2 H + 3
T − 2 T + 1
ns
ns
ns
h(CKXH-FXL)
d(FXL-CKXL)
d(CKXH-DXV)
#
Delay time, FSX low to CLKX low
Delay time, CLKX high to DX valid
−2
4
12P + 2.8 20P + 17
12P + 3 20P + 17
Disable time, DX high impedance following last data bit
from CLKX high
6
t
−2
4
ns
ns
dis(CKXH-DXHZ)
7
t
Delay time, FSX low to DX valid
L − 2 L + 4
8P + 2 16P + 17
d(FXL-DXV)
†
‡
§
P = 1/CPU clock frequency in ns. For example, when running parts at 720 MHz, use P = 1.39 ns.
For all SPI Slave modes, CLKG is programmed as 1/4 of the CPU clock by setting CLKSM = CLKGDV = 1.
S = Sample rate generator input clock = 4P if CLKSM = 1 (P = 1/CPU clock frequency)
=
Sample rate generator input clock = P_clks if CLKSM = 0 (P_clks = CLKS period)
T = CLKX period = (1 + CLKGDV) * S
H = CLKX high pulse width = (CLKGDV/2 + 1) * S if CLKGDV is even
= (CLKGDV + 1)/2 * S if CLKGDV is odd or zero
L = CLKX low pulse width = (CLKGDV/2) * S if CLKGDV is even
= (CLKGDV + 1)/2 * S if CLKGDV is odd or zero
FSRP = FSXP = 1. As a SPI Master, FSX is inverted to provide active-low slave-enable output. As a Slave, the active-low signal input on FSX
and FSR is inverted before being used internally.
CLKXM = FSXM = 1, CLKRM = FSRM = 0 for Master McBSP
CLKXM = CLKRM = FSXM = FSRM = 0 for Slave McBSP
¶
#
FSX should 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
(CLKX).
126
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TI [ TEXAS INSTRUMENTS ]
