TMS320C6202, TMS320C6202B, TMS320C6203, TMS320C6204
FIXED-POINT DIGITAL SIGNAL PROCESSORS
SPRS104A – OCTOBER 1999 – REVISED MARCH 2000
55
POST OFFICE BOX 1443 • HOUSTON, TEXAS 77251–1443
EXPANSION BUS ASYNCHRONOUS PERIPHERAL TIMING
timing requirements for asynchronous peripheral cycles
†‡§¶
(see Figure 31–Figure 34)
NO.
-200
-250
-300
UNIT
MIN MAX
3 t
su(XDV-XREH)
Setup time, XDx valid before XRE high 4.5 ns
4 t
h(XREH-XDV)
Hold time, XDx valid after XRE high 1 ns
6 t
su(XRDYH-XREL)
Setup time, XRDY high before XRE low –[(RST – 3) * P – 6] ns
7 t
h(XREL-XRDYH)
Hold time, XRDY high after XRE low (RST – 3) * P + 2 ns
9 t
su(XRDYL-XREL)
Setup time, XRDY low before XRE low –[(RST – 3) * P – 6] ns
10 t
h(XREL-XRDYL)
Hold time, XRDY low after XRE low (RST – 3) * P + 2 ns
11 t
w(XRDYH)
Pulse width, XRDY high 2P ns
15 t
su(XRDYH-XWEL)
Setup time, XRDY high before XWE low –[(WST – 3) * P – 6] ns
16 t
h(XWEL-XRDYH)
Hold time, XRDY high after XWE low (WST – 3) * P + 2 ns
18 t
su(XRDYL-XWEL)
Setup time, XRDY low before XWE low –[(WST – 3) * P – 6] ns
19 t
h(XWEL-XRDYL)
Hold time, XRDY low after XWE low (WST – 3) * P + 2 ns
†
To ensure data setup time, simply program the strobe width wide enough. XRDY is internally synchronized. If XRDY does meet setup or hold
time, it may be recognized in the current cycle or the next cycle. Thus, XRDY can be an asynchronous input.
‡
RS = Read Setup, RST = Read Strobe, RH = Read Hold, WS = Write Setup, WST = Write Strobe, WH = Write Hold. These parameters are
programmed via the XBUS XCE space control registers.
§
P = 1/CPU clock frequency in ns. For example, when running parts at 250 MHz, use P = 4 ns.
¶
The sum of RS and RST (or WS and WST) must be a minimum of 4 in order to use XRDY input to extend strobe width.
switching characteristics for asynchronous peripheral cycles
द#
(see Figure 31–Figure 34)
NO. PARAMETER
-200
-250
-300
UNIT
MIN TYP MAX
1 t
osu(SELV-XREL)
Output setup time, select signals valid to XRE low RS * P – 2 ns
2 t
oh(XREH-SELIV)
Output hold time, XRE low to select signals invalid RH * P – 2 ns
5 t
w(XREL)
Pulse width, XRE low RST * P ns
8 t
d(XRDYH-XREH)
Delay time, XRDY high to XRE high 3P 4P + 5 ns
12 t
osu(SELV-XWEL)
Output setup time, select signals valid to XWE low WS * P – 2 ns
13 t
oh(XWEH-SELIV)
Output hold time, XWE low to select signals invalid WH * P – 2 ns
14 t
w(XWEL)
Pulse width, XWE low WST * P ns
17 t
d(XRDYH-XWEH)
Delay time, XRDY high to XWE high 3P 4P + 5 ns
‡
RS = Read Setup, RST = Read Strobe, RH = Read Hold, WS = Write Setup, WST = Write Strobe, WH = Write Hold. These parameters are
programmed via the XBUS XCE space control registers.
§
P = 1/CPU clock frequency in ns. For example, when running parts at 250 MHz, use P = 4 ns.
¶
The sum of RS and RST (or WS and WST) must be a minimum of 4 in order to use XRDY input to extend strobe width.
#
Select signals include: XCEx
, XBE[3:0], XA[5:2], XOE; and for writes, include XD[31:0], with the exception that XCEx can stay active for an
additional 7P ns following the end of the cycle.
PR