Z80180 Datasheet, PDF (166/326 Pages) Zilog, Inc. – Z8018x Family MPU

Z 8018x Fam ily
M PU Us e r M anual
151
IEF1
EF
CSI/O
Interrupt Request
EIE
Figure 58. CSI/O Interrupt Request Generation
CSI/O Operation
The CSI/O is operated using status polling or interrupt driven algorithms.
• Transmit–Polling
a. Poll the TE bit in CNTR until TE = 0.
b. Write the transmit data into TRDR.
c. Set the TE bit in CNTR to 1.
d. Repeat steps 1 to 3 for each transmit data byte.
• Transmit–Interrupts
a. Poll the TE bit in CNTR until TE = 0.
b. Write the first transmit data byte into TRDR.
c. Set the TE and EIE bits in CNTR to 1.
d. When the transmit interrupt occurs, write the next transmit data
byte into TRDR.
e. Set the TE bit in CNTR to 1.
f. Repeat steps 4 and 5 for each transmit data byte.
• Receive –Polling
a. Poll the RE bit in CNTR until RE = 0.
b. Set the RE bit in CNTR to 1.
UM005001-ZMP0400