Datasheet

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PIC18F87J50 FAMILY

11.2.5.1 READ FROM SLAVE PORT

When chip select is active and a read strobe occurs

(PMCS = 1 and PMRD = 1), the data from one of the

four output bytes is presented onto PMD<7:0>. Which

byte is read depends on the 2-bit address placed on

ADDR[1:0]. Table 11-2 shows the corresponding

output registers and their associated address. When an

output buffer is read, the corresponding OBxE bit is set.

The OBxE flag bit is set when all the buffers are empty.

If any buffer is already empty, OBxE = 1, the next read

to that buffer will generate an OBUF event.

FIGURE 11-7: PARALLEL SLAVE PORT READ WAVEFORMS

11.2.5.2 WRITE TO SLAVE PORT

When chip select is active and a write strobe occurs

(PMCS = 1 and PMWR = 1), the data from PMD<7:0>

is captured into one of the four input buffer bytes.

Which byte is written depends on the 2-bit address

placed on ADDRL[1:0]. Table 11-2 shows the corre-

sponding input registers and their associated address.

When an input buffer is written, the corresponding IBxF

bit is set. The IBF flag bit is set when all the buffers are

written. If any buffer is already written (IBxF = 1), the

next write strobe to that buffer will generate an OBUF

event and the byte will be discarded.

FIGURE 11-8: PARALLEL SLAVE PORT WRITE WAVEFORMS

PMCS

| Q4 | Q1 | Q2 | Q3 | Q4

PMWR

PMRD

PMD<7:0>

PMA<1:0>

OBE

PMPIF