S e r i a l C h a n n e l r e g i s t e r s

Bits

Access

Mnemonic

Reset

Description

 

 

 

 

TBC continued

 

 

The TBC field is set when the last character in

 

 

 

 

the transmit FIFO has been shifted out of the

 

 

 

 

shift register and the FIFO currently is empty.

 

 

 

 

While the TBC field is active, the TRDY bit is

 

 

 

 

not active. To activate TRDY (to write to the

 

 

 

 

data FIFO), TBC must be acknowledged. When

 

 

 

 

operating in DMA mode, the interlock between

 

 

 

 

TBC and TRDY is handled automatically in

 

 

 

 

hardware.

 

 

 

 

 

D00

R

TEMPTY

0

Transmit FIFO empty

 

 

 

 

Indicates that the transmit data FIFO is

currently empty. TEMPTY simply reports the status of the FIFO; it does not indicate that the character currently in the transmit shift register has been transmitted. The TBC bit must be used for the all sent condition.

Table 89: Serial Channel Status Register A bit definition

Serial Channel 1, 2 Bit-Rate registers

Address: FFD0 000C / 4C

The serial channel bit rate registers configure the bit-rate for each serial channel.

The serial channel can be configured to operate using an internal or external timing reference. When configured for internal timing, the timing reference is provided by the bit-rate generator. When configured for external timing, the timing reference is provided by the PORTC signals RXCLK and TXCLK.

The serial channel can be configured to operate in either 1X (synchronous) mode or 16X (asynchronous) mode. When using the internal bit-rate generator, the frequency must be configured properly to match the mode being used.

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

EBIT

T

RX

TX

RX

TX

CLKM

MODE

SRC

SRC

EXT

EXT

UX

 

 

 

 

 

 

 

 

TXC

RXC

Rsvd

INV

INV

 

 

 

 

TDCR

Rsvd

RDCR

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Rsvd TICS RSVD RICS Rsvd

NREG

2 4 4

N S 7 5 2 0 H a r d w a r e R e f e r e n c e , R e v . D 0 3 / 2 0 0 6

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Digi NS7520 manual Serial Channel 1, 2 Bit-Rate registers, Address FFD0 000C / 4C, Tempty