Jameco-electronics Rabbit 3000 Manual do Utilizador descarregar pdf (Página 323)

314 Rabbit 3000 Microprocessor

B.1.14 Quadrature Decoder Improvements

The quadrature decoder counters can now be expanded to 10 bits instead of 8 bits. This is

controlled by bit 5 in QDCR, listed in Table B-28. The additional two bits can be read in

the QDCxHR registers, listed in Table B-29.

NOTE: Bit 5 of QDCR was always written with a zero in the original Rabbit 3000 chip.

Table B-28. Quadrature Decoder Control Register

Quadrature Decoder Control Register (QDCR) (Address = 0x0091)

Bit(s) Value Description

7:6 00

Disable Quadrature Decoder 2 inputs. Writing a new value to these bits will not

cause Quadrature Decoder 2 to increment or decrement.

01 This bit combination is reserved and should not be used.

10 Quadrature Decoder 2 inputs from Port F bits 3 and 2.

11 Quadrature Decoder 2 inputs from Port F bits 7 and 6.

5 0 Eight bit quadrature decoder counters.

1 Ten bit quadrature decoder counters.

4 This bit is reserved and should be written as zero.

3:2 00

Disable Quadrature Decoder 1 inputs. Writing a new value to these bits will not

cause Quadrature Decoder 1 to increment or decrement.

01 This bit combination is reserved and should not be used.

10 Quadrature Decoder 1 inputs from Port F bits 1 and 0.

11 Quadrature Decoder 1 inputs from Port F bits 5 and 4.

1:0 00 Quadrature Decoder interrupts are disabled.

01 Quadrature Decoder interrupt use Interrupt Priority 1.

10 Quadrature Decoder interrupt use Interrupt Priority 2.

11 Quadrature Decoder interrupt use Interrupt Priority 3.

Table B-29. Quadrature Decoder Count High Register

Quadrature Decoder Count High Register (QDC1HR) (Address = 0x0095)

(QDC2HR) (Address = 0x0097)

Bit(s) Value Description

7:2 read These bits are reserved and will always read as zeros.

1:0 read The current value of bits 9-8 of the Quadrature Decoder counter is reported.

1 2 ... 318 319 320 321 322 323 324 325 326 327 328 ... 348 349

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