AP500/AP520/AP521 ACROPACK
USER
’S MANUAL
Acromag, Inc. Tel: 248-295-0310
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www.acromag.com
Bits if 6, 7, or 8 data bits selected.
3
Parity
Enable
0 = Parity Disabled 1 = Parity Enabled
A parity bit is generated and checked for between
the last data word bit and the stop bit.
4
Even-
Parity
Select
0 = Odd Parity
1 = Even Parity
5
Stick
Parity
0 = Disabled, 1 = Enabled
When parity is enabled, stick parity causes the
transmission and reception of a parity bit to be in
the opposite state from the value selected via bit
4. This is used as a diagnostic tool to force parity
to a known state and allow the receiver to check
the parity bit in a known state.
6
Break
Control
0 = Break Disabled, 1 = Break Enabled
When break is enabled, the serial output line
(TxD) is forced to the space state (low). This bit
acts only on the serial output and does not affect
transmitter logic. For example, if the following
sequence is used, no invalid characters are
transmitted due to the presence of the break.
1. Load a zero byte in response to the
Transmitter Holding Register Empty (THRE)
status indication.
2. Set the break in response to the
next THRE status indication.
3. Wait for the transmitter to become
idle when the Transmitter Empty status signal
is set high (TEMT=1); then clear the break
when normal transmission has to be restored.
7
DLL/DLM
0 = Access Receiver Buffer
1 = Allow Access to Divisor Latches (DLL & DLM)
Note that bit 7 must be set high to access the divisor latch registers DLL &
DLM of the baud rate generator or access the Enhanced Feature Register
(EFR). Bit 7 must be low to access the Receiver Holding Register (RHR), the
Transmitter Holding Register (THR), or the Interrupt Enable Register (IER). A