z80189 ZiLOG Semiconductor, z80189 Datasheet - Page 149

• Manufacturer Part Number: z80189
• Description: Z80180, Z8s180, Z8l180 Mpu Operation
• Manufacturer: ZiLOG Semiconductor

134
UM005003-0703
Z8018x
Family MPU User Manual
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.
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
Divide Ratio
SS0
0
1
0
1
0
1
0
1
Divide Ratio
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¸
¸
¸
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external clock
1
2
4
8
16
32
64
1
, then the CKA1/
1
) these pins