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Command #04 - WriteBBitCmd
Description:
Write masked values to port B. The net result of writing masked values is that only the specified bits will be written. The resulting port condition is the logic combination of the current port state ANDed with the first term and then ORed with the second. This command can affect any number of lines on the port.
Command Format:
| Byte Number | Description |
| 0 | 04h: WriteBBitCmd |
| 1 | AND term (off term) |
| 2 | OR term (on term) |
| 3 | <not used> |
| 4 | <not used> |
| 5 | <not used> |
| 6 | <not used> |
| 7 | <not used> |
Command Format Details:
Byte 0 contains the command. Byte 1 is the AND term, byte 2 is the OR term. Byte 3 through byte 7 are unused.
Bits in the AND term that are 0 force the line to be a zero. The set bits act as a "don't care". Think of the 0 positions in the AND term as "turn off".
Bits in the OR term that are 1 force the output line high, the bits set to 0 are don't-cares. Think of the 1 positions in the OR term as "turn on".
Response Format:
| Byte Number | Description |
| 0 | 04h: InitPortsCmd |
| 1 | <not used> |
| 2 | <not used> |
| 3 | <not used> |
| 4 | <not used> |
| 5 | <not used> |
| 6 | <not used> |
| 7 | <not used> |
Response Format Details:
Byte 0 contains the command. Byte 1 through byte 7 are unused.
Example Usage:
Set every line in the port to output using the direction command. Set the entire port to FFh using the port write command.
Now set the lower nibble (lower 4 lines) low. The AND term should be F0h, the OR term would then be 00h (or even F0h).
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