S e r i a l C o n t r o l l e r M o d u l e

 

 

 

 

 

 

 

 

 

 

 

Bits

Access

Mnemonic

Reset

Description

 

 

 

 

 

 

 

D23

R/W

CTSTX

0

Enable the transmitter with active CTS

 

 

 

 

Supports hardware handshaking. When

 

 

 

 

CTSTX is set, the transmitter operates only

 

 

 

 

when the external CTS signal is in the active

 

 

 

 

state. An external device can use CTS to

 

 

 

 

temporarily stall data transmission.

 

 

 

 

 

 

D22

R/W

RTSRX

0

Enable active RTS (only when RX FIFO has

 

 

 

 

space)

 

 

 

 

Supports hardware handshaking. When

 

 

 

 

RTSRX is set, the RTS output provides the

 

 

 

 

receiver FIFO almost-full condition. When the

 

 

 

 

receiver FIFO backs up, the RTS signal is

 

 

 

 

dropped. The RTS output stalls an external

 

 

 

 

transmitter from delivering data.

 

 

 

 

 

 

D21

R/W

RL

0

Remote loopback

 

 

 

 

Provides a remote loopback feature. When set

 

 

 

 

to 1, the TXD transmit output is connected to

 

 

 

 

the RXD receive input. The RL field

 

 

 

 

immediately echoes receive data back as

 

 

 

 

transmit data.

 

 

 

 

Primarily used as test vehicle for external data

 

 

 

 

equipment.

 

 

 

 

 

 

D20

R/W

LL

0

Local loopback

 

 

 

 

Provides an internal local loopback feature.

 

 

 

 

When set to 1, the internal receive data stream

 

 

 

 

is connected to the TXD output signal. This

 

 

 

 

field connects the serial channel receiver

 

 

 

 

directly to the serial channel transmitter.

 

 

 

 

Primarily used as a test vehicle for the serial

 

 

 

 

channel driver firmware.

 

 

 

 

 

 

D19:18

R/W

OUT1/OUT2

0

General-purpose output 1/General-purpose

 

 

 

 

output 2

The OUT1 and OUT2 fields provide extra, miscellaneous serial channel control signal outputs. The OUT1 and OUT2 signals can be routed through PORTA and PORTC pins using PORTA and PORTC special function modes.

Table 85: Serial Channel Control Register A

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Image 241
Digi NS7520 manual Enable the transmitter with active CTS, Remote loopback, Local loopback, Output