Z8S180 Zilog., Z8S180 Datasheet - Page 149

• Manufacturer Part Number: Z8S180
• Description: ENHANCED Z180 MICROPROCESSOR
• Manufacturer: Zilog.

134
UM005001-ZMP0400
Z 8018x Fam il y
M PU Us e r M anual
pins are initialized as ASCI data clock inputs. If SS2, SS1 and SS0 are
reprogrammed (any other value than SS2, SS1, SS0 =
become ASCI data clock inputs. However, if DMAC channel 0 is
configured to perform memory to/from I/O (and memory mapped I/O)
transfers the CKA0/ DREQ0 pin reverts to DMA control signals
regardless of SS2, SS1, SS0 programming.
Also, if the CKA1D bit in the CNTLA register is
TEND0 reverts to the DMA Control output function regardless of SS2,
SS1 and SS0 programming. Final data clock rates are based on CTS/PS
(prescale), DR, SS2, SS1, SS0 and the Z8X180 system clock frequency
(Reference Table 19).
Table 18. Divide Ratio
Each ASCI channel control register B configures multiprocessor mode,
parity and baud rate selection.
SS2
0
0
0
0
1
1
1
1
SS1
0
0
1
1
0
0
1
1
SS0
0
1
0
1
0
1
0
1
Divide Ratio
external clock
1
2
4
8
16
32
64
1
, then the CKA1/
1
) these pins