R2025S/D
Start Condition
Stop Condition
SCL
SDA
tHD;STA
tSU;STO
(2) Data transmission and its acknowledge
After Start condition is entered, data is transmitted by 1byte (8bits). Any bytes of data may be serially
transmitted. The receiving side will send an acknowledge signal to the transmission side each time 8bit data is
transmitted. The acknowledge signal is sent immediately after falling to “L” of SCL 8bit clock pulses of data is
transmitted, by releasing the SDA by the transmission side that has asserted the bus at that time and by turning
SDA to “L” by receiving side. When transmission of 1byte data next to preceding 1byte of data is received the
receiving side releases the SDA pin at falling edge of the SCL 9bit of clock pulses or when the receiving side
switches to the transmission side it starts data transmission. When the master is receiving side, it generates no
acknowledge signal after last 1byte of data from the slave to tell the transmitter that data transmission has
completed. The slave side (transmission side) continues to release the SDA pin so that the master will be able to
generate Stop Condition, after falling edge of the SCL 9bit of clock pulses.
SCL
from the master
1
2
8
9
SDA from
the transmission side
SDA from
the receiving side
Start
Condition
Acknowledge
signal
22
RICOH [ RICOH ELECTRONICS DEVICES DIVISION ]
