
SM320C6701EP, SM320C6701MECHEP
FLOATINGPOINT DIGITAL SIGNAL PROCESSOR
SGUS042A MAY 1998 REVISED APRIL 2004
52
POST OFFICE BOX 1443
HOUSTON, TEXAS 772511443
MULTICHANNEL BUFFERED SERIAL PORT TIMING (CONTINUED)
timing requirements for McBSP as SPI master or slave: CLKSTP = 10b, CLKXP = 0 (see Figure 33)
NO.
C6701-120
C6701-167
UNIT
NO.
MASTER
SLAVE
UNIT
MIN
MAX
MIN
MAX
4
tsu(DRV-CKXL)
Setup time, DR valid before CLKX low
12
2 3P
ns
5
th(CKXL-DRV)
Hold time, DR valid after CLKX low
4
5 + 6P
ns
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.
switching characteristics for McBSP as SPI master or slave: CLKSTP = 10b, CLKXP = 0
(see Figure 33)
NO.
PARAMETER
C6701-120
C6701-167
UNIT
NO.
PARAMETER
MASTER§
SLAVE
UNIT
MIN
MAX
MIN
MAX
1
th(CKXL-FXL)
Hold time, FSX low after CLKX low
T 4
T + 4
ns
2
td(FXL-CKXH)
Delay time, FSX low to CLKX high#
L 4
L + 4
ns
3
td(CKXH-DXV)
Delay time, CLKX high to DX valid
4
3P + 1
5P + 17
ns
6
tdis(CKXL-DXHZ)
Disable time, DX high impedance following last data bit from
CLKX low
L 2
L + 3
ns
7
tdis(FXH-DXHZ)
Disable time, DX high impedance following last data bit from FSX
high
P + 4
3P + 17
ns
8
td(FXL-DXV)
Delay time, FSX low to DX valid
2P + 1
4P + 13
ns
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).