UPC1857ACT datasheet(24/44 Pages) NEC

24 / 44 page

µµµµPC1857A

4.4.6 Automatic increment

The automatic increment function can be turned ON/OFF by using the data of bit D6 of subaddresses 01H through

04H.

This is effective when transmitting data successively (refer to 3.2.2 Successive data transfer).

Figure 4-6. Automatic Increment

Subaddress

01H-04H

Don't care

Automatic

increment

Don't care

Automatic increment: OFF

Automatic increment: ON

Automatic increment

Caution Subaddress 00H does not have an automatic increment function. It is always set to ON.

The automatic increment function automatically increments the subaddress when data is transferred successively.

Automatic increment ON : The subaddress is automatically incremented immediately after byte data with D6 = 1

has been transferred.

This setting is useful if the data at every subaddress is to be set at once for

initialization. The subaddress is always incremented immediately after the data of

subaddress: 00H has been transferred.

Automatic increment OFF : The subaddress is fixed immediately after byte data with D6 = 0 has been

transferred. This setting is useful when the data at the same subaddress is to be

successively changed, for example to turn up/down the volume.

There is an automatic increment function ON/OFF bit in subaddresses 01H through 04H.

Incrementing

subaddresses is individually controlled by the automatic increment function ON/OFF bit of each subaddress.

For example, if the automatic increment function of subaddress 01H is turned ON, and that of subaddress 02H is

turned OFF, the subaddress is automatically incremented from 01H to 02H, and is fixed to 02H.

Even if the automatic increment function ON/OFF bit of subaddress 04H is set to ON, the subaddress is not

incremented. If the next data is transferred after the data of 04H has been set (acknowledge bit: L), acknowledge

enters the NAK status (acknowledge bit: H), and data transfer from the host CPU is stopped.

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