SMJ320C6701_07 Datasheet, PDF (55/64 Pages) Texas Instruments – FLOATING-POINT DIGITAL SIGNAL PROCESSOR

SMJ320C6701
FLOATINGĆPOINT DIGITAL SIGNAL PROCESSOR
SGUS030B – APRIL 2000 – REVISED MAY 2001
MULTICHANNEL BUFFERED SERIAL PORT TIMING (CONTINUED)
switching characteristics for McBSP as SPI master or slave: CLKSTP = 11b, CLKXP = 0^†‡
(see Figure 34)
NO.
PARAMETER
1 th(CKXL-FXL)
2 td(FXL-CKXH)
Hold time, FSX low after CLKX low^¶
Delay time, FSX low to CLKX high#
3 td(CKXL-DXV)
Delay time, CLKX low to DX valid
6
tdis(CKXL-DXHZ)
Disable time, DX high impedance following last data bit
from CLKX low
’C6701-14
’C6701-16
MASTER^§
SLAVE
MIN MAX
MIN
MAX
L–4 L+4
T–4 T+4
–4
4 3P + 1 5P + 17
UNIT
ns
ns
ns
*–2
*4 *3P + 4 *5P + 17 ns
7 td(FXL-DXV)
Delay time, FSX low to DX valid
*H – 2 *H + 3 2P + 1 4P + 13 ns
*This parameter is not tested.
† _{The effects of internal clock jitter are included at test. There is no need to adjust timing numbers for internal clock jitter. P = 1/CPU clock frequency}
in ns. For example, when running parts at 167 MHz, use P = 6 ns.
‡ _{For all SPI slave modes, CLKG is programmed as 1/2 of the CPU clock by setting CLKSM = CLKGDV = 1.}
§ _{S = sample rate generator input clock = P 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).
CLKX
FSX
DX
DR
1
6
Bit 0
Bit 0
2
7
3
Bit(n-1)
(n-2)
(n-3)
(n-4)
4
5
Bit(n-1)
(n-2)
(n-3)
(n-4)
Figure 34. McBSP Timing as SPI Master or Slave: CLKSTP = 11b, CLKXP = 0
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