z80189 ZiLOG Semiconductor, z80189 Datasheet - Page 156

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

ASCI to/from DMAC Operation
Operation of the ASCI with the on-chip DMAC channel 0 requires that the
DMAC be correctly configured to use the ASCI flags as DMA request signals.
ASCI and RESET
During RESET, the ASCI status and control registers are initialized as
defined in the individual register descriptions.
Receive and Transmit operations are stopped during RESET. However,
the contents of the transmit and receive data registers (TDR and RDR) are
not changed by RESET.
ASCI Clock
When in external clock input mode, the external clock is directly input to
the sampling rate (¸16/¸64) as depicted in Figure 56.
External Clock
Figure 56.
Internal Clock
fc £ Phi
¸
Phi
40
ASCI Clock
Baud Rate Selection Prescaler
¸
1 to
¸
64
¸
10
Family MPU User Manual
¸
30
Sampling Rate
¸
16
UM005003-0703
¸
64
Z8018x
141