19 Serial communication
RX8130CE
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ETM50E-07
Seiko Epson Corporation
61
19.6 I
2
C-Bus protocol
In the following sequence descriptions, it is assumed that the CPU is the master and the RX8130CE is the slave.
1)
Address specification write sequence
Since the RX8130CE includes an address auto increment function, once the initial address has been specified, the
RX8130 increments (by one byte) the receive address each time data is transferred.
Address circulation of auto
increment function.
10h ->1Fh -> 10h
20h ->2Fh -> 20h
30h ->3Fh -> 30h
(1) CPU transfers start condition [S].
(2) CPU transmits the RX8130CE's slave address with the R/W bit set to write mode.
(3) Check for ACK signal from RX8130CE.
(4) CPU transmits write address to RX8130CE.
(5) Check for ACK signal from RX8130CE.
(6) CPU transfers write data to the address specified at (4) above.
(7) Check for ACK signal from RX8130CE.
(8) Repeat (6) and (7) if necessary. Addresses are automatically incremented.
(9) CPU transfers stop condition [P].
S
(1)
0
R/W
0
(3)
Address
(4)
0
(5)
0
Data
(8)
P
(9)
ACK signal from8130CE
Data
(6)
0
(7)
(2)
Slave address
2)
Address specification read sequence
After using write mode to write the address to be read, set read mode to read the actual data.
(1) CPU transfers start condition [S].
(2) CPU transmits the RX8130CE's slave address with the R/W bit set to write mode.
(3) Check for ACK signal from RX8130CE.
(4) CPU transfers address for reading from RX8130CE.
(5) Check for ACK signal from RX8130CE.
(6) CPU transfers RESTART condition [Sr] (in which case, CPU does not transfer a STOP condition [P]).
(7) CPU transfers RX8130'CEs slave address with the R/W bit set to read mode.
(8) Check for ACK signal from RX8130CE (from this point on, the CPU is the receiver and the RX8130 is the
transmitter).
(9) Data from address specified at (4) above is output by the RX8130.
(10) CPU transfers ACK signal to RX8130CE.
(11) Repeat (9) and (10) if necessary. Read addresses are automatically incremented.