UT1553B/BCRT-ACA0 Просмотр технического описания (PDF) - Aeroflex UTMC

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UT1553B/BCRT-ACA0

UT1553B BCRT bus controller/remote terminal/monitor. Lead finish optional. Total dose none.

Aeroflex UTMC 

3.0 Internal Registers

The BCRT’s internal registers (see table 1 on pages 16-17)

enable the CPU to control the actions of the BCRT while

maintaining low DMA overhead by the BCRT. All functions

are active high and ignored when low unless stated

#0 Control Register

Bit

Number

Description

otherwise. Functions and parameters are used in both RT

and BC modes except where indicated. Registers are

addressed by the binary equivalent of their decimal number.

For example, Register 1 is addressed as 0001B. Register

usage is defined as follows:

BITs15-12

BIT 11

BIT 10

BIT 9

BIT 8

BIT 7

BITs 6-5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

Reserved.

Enable External Override. For use in multi-redundant systems. This bit enables the EXTOVR pin.

BC/RT Select. This function selects between the Bus Controller and Remote Terminal operation modes. It

overrides the external BCRTSEL input setting if the Change Lock-Out function is not used. A reset

operation must be performed when changing between BC and RT modes. This bit is write-only.

(BC) Retry on Alternate Bus. This bit enables an automatic retry to operate on alternate buses. For example, if on

bus A, with two automatic retries programmed, the automatic retries occur on bus B.

(RT) Channel B Enable. When set, this bit enables Channel B operation.

(BC) No significance.

(RT) Channel A Enable. When set, this bit enables Channel A operation.

(BC) Channel Select A/B. When set, this bit selects Channel A.

(BC) Retry Count. These bits program the number (1-4) of retries to attempt. (00 = 1 retry,11 = 4 retries)

(BC) Retry on Bus Controller Message Error. This bit enables automatic retries on an error the Bus Controller

detects (see the Bus Controller Architecture section, page 27).

(BC) Retry on Time-Out. This bit enables an automatic retry on a response time-out condition.

(BC) Retry on Message Error. This bit enables an automatic retry when the Message Error bit is set in the RT’s

status word response.

(BC) Retry on Busy. This bit enables automatic retry on a received Busy bit in an RT status word response.

Start Enable. In the BC mode, this bit starts/restarts Command Block execution. In the RT mode, it enables the

BCRT to receive a valid command. RT operation does not start until a valid command is received. When using

this function:

• Restart the BCRT after each Master Reset or programmed reset.

• This bit is not readable; verify operation by reading bit 0 of the BCRT’s Status Register.

BCRT-12

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