AP500/AP520/AP521 ACROPACK
USER
’S MANUAL
Acromag, Inc. Tel: 248-295-0310
- 39 - http://www.acromag.com
- 39 -
www.acromag.com
Control
Enable Automatic CTS flow control. The CTS pin
can be monitored for remote buffer overflow
indication. When automatic CTS hardware
flow control is enabled, a CTS transition from
logic “0” to a logic “1” to indicate a flow
control request, ISR bit-5 will be set to a logic
“1” (if enabled via IER bit6-7), and transmission
of data will be suspended as soon as the stop
bit of the character in process is shifted out.
Transmission is resumed after the CTS input
returns to a logic “0”, indicating more data
may be sent.
For the AP521 model RTS is used to enable its corresponding transmitter for
output of the TxD signal. The RTS signals do not have transmitter output
paths on this model. The CTS signals do not have a receiver input path on
the AP521 model. A power-up or system reset sets all EFR bits to 0. The CTS
and RTS signals are available on the AP500 and AP520 models.
3.2.15 XON/XOFF-1,2 Registers (R/W)
These registers hold the programmed XON and XOFF characters for software
flow control. XON or XOFF characters may be 1 or 2 bytes long. The UART
compares incoming data to these values and restarts (XON) or suspends
(XOFF) data transmission when a match is detected. All XON/XOFF bits are
set to 0 upon power-up or system reset.
3.3 Model Identification
The PCI Device ID and MPIOLVL[0] registers can be used to determine the
exact model of the AP5XX module as shown in the table below.
Table 3.14 Model ID
Model
Device ID
MPIOLVL[0]
500
0x0354
0
520
0x0358
0
521
0x0358
1
