Z85233 Datasheet, PDF (173/317 Pages) Zilog, Inc. – The Zilog SCC Serial Communication Controller

Application Note
The Z180™ Interfaced with the SCC at MHZ
INPUT/OUTPUT CYCLES
Although the SCC is a universal design, certain timing
parameters differ from the Z180 timing. The following
subsections discuss the I/O interface for the Z180 MPU
and SCC.
Z180 MPU to SCC Interface
Table 7 shows key parameters of the 10 MHz SCC for I/O
read/write cycles.
Table 7. 10 MHz SCC Timing Parameters for I/O Read/Write Cycle (Worst Case)
No Symbol
6 TsA(WR)
7 ThA(WR)
8 TsA(RD)
9 ThA(RD)
16 TsCEI(WR)
17 ThCE(WR)
19 TsCEI(RD)
20 ThCE(RD)
22 TwRDI
25 TdRDf(DR)
27 TdA(DR)
28 TwWRI
29 TsDW(WR)
30 TdWR(W)
Parameter
Address to /WR Low Setup
Address to /WR High Hold
Address to /RD Low Setup
Address to /RD High Hold
/CE Low to /WR Low Setup
/CE to /WR High Hold
/CE Low to /RD Low Setup
/CE to /RD High Hold
/RD Low Width
/RD Low to Read Data Valid
Address to Read Data Valid
/WR Low Width
Write Data to /WR Low Setup
Write Data to /WR High Hold
Min
Max
50
0
50
0
0
0
0
0
125
120
180
125
10
0
Units
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
SCC I/O Read/Write Cycle
Assume that the Z180 MPU’s /IOC bit in the OMCR
(Operation Mode Control Register) clears to 0 (this
condition is a Z80 compatible timing mode for /IORQ and
/RD). The following are several design points to consider
(also see Table 3).
I/O Read Cycle
Parameters 8 and 9 mean that Address is stable 20 ns
before the falling edge of /RD and until /RD goes inactive.
Parameters 19 and 20 mean that /CE is stable at the falling
edge of /RD and until /RD goes inactive.
Parameter 22 means the /RD pulse width is wider than
125 ns.
Parameters 25 and 27 mean that Read data is available on
the data bus 120 ns later than the falling edge of /RD and
180 ns from a stable Address.
I/O Write Cycle
Parameters 6 and 7 mean that Address is stable 50 ns
before the falling edge of /WR and is stable until /WR goes
inactive.
Parameters 16 and 17 mean that /CE is stable at the falling
edge of /WR and is stable until /W goes inactive.
Parameter 28 means /WR pulse width is wider than 125
ns.
Parameters 28 and 29 mean that Write data is on the data
bus 10 ns before the falling edge of /WR. It is stable until
the rising edge of /WR.
Tables 8 and 9 show the worst case SCC parameters
calculating Z180 parameters at 10 MHz.
6-38
UM010901-0601