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C2K User’s Guide
Resources
5.2.5 USART Registers
The FPGA provides six synchronous/asynchronous transmitter/receiver ports. Each operates
independently, supporting transmit enable, transmit data, transmit clock, receive data, and receive
clock. The ports each can be configured to operate as standard asynchronous character oriented
UARTs, or as USARTs. As a USART, the receive data must be aligned to the receive clock. The
transmit data is aligned to the transmit clock. The transmit clock may be sourced from the internal
baud-rate-generator for that specific port, or may be sourced from the port’s receive clock.
NOTE:
Standard 16550 DMA features are not provided
Table 5-11 lists the USART Registers.
USART Control/Mode Register
The USART Control/Mode Register sets the extended configuration parameters for the USART
ports.
Table 5-11
USART Resister
Offset
Register
Description
0xF0
USART 0 Control/Mode
0xF2
USART 1 Control/Mode
0xF4
USART 2 Control/Mode
0xF6
USART 3 Control/Mode
0xF8
USART 4Control/Mode
0xFA
USART 5 Control/Mode
0xFC
Unused
0xFE
Unused
Address offset:
0xF0–0xFE
Access:
Read/write
Bits
Field
Default
Description
15 - 8
Not used
-
Not used
7
ACTIVATE
0
Logical Device Activation—enables the logical device.
0 = disable
1 = enable
6
Not used
-
Not used
5
TEST_FE
0
Framing Error Test Mode—truncates transmitted stop bit
to one-half bit time in asynchronous mode; stop bit is
omitted completely in synchronous mode.
0 = stop bit is not altered
1 = stop bit is truncated/omitted
NOTE:
This bit must be cleared (0) for normal operation.
4
TEST_PE
0
Parity Error Test Mode—inverts transmitted parity bit.
0 = parity bit non-inverted
1 = parity bit inverted
NOTE:
This bit must be cleared (0) for normal operation.
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