Dio/dma interface, Timing requirements (see figure 18) – Texas Instruments THUNDER TNETX3270 User Manual
Page 58
TNETX3270
ThunderSWITCH
24/3 ETHERNET
SWITCH
WITH 24 10-MBIT/S PORTS AND 3 10-/100-MBIT/S PORTS
SPWS043B – NOVEMBER 1997 – REVISED APRIL 1999
58
POST OFFICE BOX 655303
•
DALLAS, TEXAS 75265
DIO/DMA interface
The DIO interface is asynchronous to allow easy adaptation to a range of microprocessor devices and computer
system interfaces.
DIO/DMA write cycle
timing requirements (see Figure 18)
NO.
MIN
MAX
UNIT
1
tw(SCSL)
Pulse duration, SCS low
24
ns
2
tw(SCSH)
Pulse duration, SCS high
12
ns
3
tsu(SRNW)
Setup time, SRNW low before SCS
↓
0
ns
4
tsu(SAD)
Setup time, SAD1–SAD0 and SDMA valid before SCS
↓
0
ns
5
tsu(SDATA)
Setup time, SDATA7–SDATA0 valid before SCS
↓
0
ns
operating characteristics over recommended operating conditions (see Figure 18)
NO.
PARAMETER
MIN
MAX
UNIT
6
tw(SRDYH)
Pulse duration, SRDY high
12
ns
7
td(SRNW)
Delay time, from SRDY
↓
to SRNW
↑
0
ns
8
td(SAD)
Delay time, from SRDY
↓
to SAD1–SAD0 and SDMA invalid
0
ns
9
td(SDATA)
Delay time, from SRDY
↓
to SDATA7–SDATA0 invalid
0
ns
10
td(SCS)
Delay time, from SRDY
↓
to SCS
↑
0
ns
11
td(SRDY)1
Delay time, from SCS
↓
to SRDY
↑
0
ns
12
td(SRDY)2
Delay time, from SCS
↓
to SRDY
↓
†
0
ns
13
td(SRDY)3
Delay time, from SCS
↑
to SRDY
↑
0
24
ns
† When the switch is performing certain internal operations (e.g., EEPROM load), there may be a considerable delay (approximately 25–100 ms)
between SCS being asserted and SRDY being asserted.
Z
SRNW
(input)
SCS
(input)
ООООО
ООООО
ООО
ООО
12
1
4
5
3
11
10
8
7
9
6
13
SAD1–SAD0,
SDMA
(inputs)
SDATA7–
SDATA0
(inputs)
SRDY
(output)
2
ОООООООО
ОООООООО
ОООООООО
ОООООООО
Z
Z
Figure 18. DIO/DMA Write Cycle