EM6812F2TP24B datasheet(14/81 Pages) EMMICRO

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EM6812

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5.3.2

External Write Access to DPR

A write access from external uses the control signals ExtWen, ExtCen and the address signals ExtAddr[1:0] from the port A

to write a value given on the port B into the DPR location inside the EM6812.

Setting EnDualRam=’1’ in RegCfgPB and then configure port A and port B to allow an external circuitry to drive the

necessary control and data lines for DPR operation.

Figure 6. DPR, Write into the EM6812

Data are written into the DPR on the rising edge of ExtCen. While ExtWen is high the selected address location is write

protected against CPU writes.

5.3.3

Read Access from DPR

A Read access from external uses the control signals ExtWen, ExtCen and the address signals ExtAddr[1:0] from the port A

to output the addressed DPR value on the port B.

First set the necessary port A configuration to allow an external circuitry to drive the input port. As soon as ExtCen becomes

high (and ExtWen is low) the port B will become output and drive the currently selected DPR data value.

Figure 7. DPR, Read from the EM6812

While ExtCen is high the selected DPR memory location is write protected to guarantee the value read by the external

device.

ExtAddr[1:0]

ExtWen

ExtCen

Mem cell @h000D

ExtData[7:0]

ExtAddr[1:0]

ExtWen

ExtData[7:0]

ExtCen

Mem cell @h000D

EM6812F2TP24B Datasheet(PDF) 14 Page - EM Microelectronic - MARIN SA