z80189 ZiLOG Semiconductor, z80189 Datasheet - Page 171

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

156
UM005003-0703
Z8018x
Family MPU User Manual
Programmable Reload Timer (PRT)
Figure 62.
The Z8X180 contains a two channel 16-bit Programmable Reload Timer.
Each PRT channel contains a 16-bit down counter and a 16-bit reload
register. The down counter is directly read and written and a down counter
overflow interrupt can be programmably enabled or disabled. Also, PRT
channel 1 features a TOUT output pin (multiplexed with A18) which can be
set High, Low, or toggled. Thus, PRT1 can perform programmable output
waveform generation.
PRT Block Diagram
The PRT block diagram is depicted in Figure 63. The two channels
feature separate timer data and reload registers and a common status/
CKS
RXS
RE
EF
CSI/O Receive Timing–External Clock
11.5f
Sampling
16.5f
LSB
11.5f
16.5f
11.5f
16.5f
Read or write of CSI/O
11.5f
Transmit/Receive
16.5f
Data Register
MSB