FMS9874 Datasheet, PDF (16/25 Pages) Fairchild Semiconductor – Graphics Digitizer - 3x8-Bit, 108Ms/s Triple Video A/D Converter with Clamps

PRODUCT SPECIFICATION
After each byte is read, the pointer auto-increments to allow
multiple data byte transfers within one read cycle.
Preceding each slave write, there must be a start cycle.
Following the pointer byte there should be a stop cycle.
After the last read, there must be a stop cycle comprising
a LOW-to-HIGH transition of SDA while SCL is HIGH.
(see Figure 18, right waveform)
A repeated start signal occurs when the master device driv-
ing the serial interface generates a start signal without first
generating a stop signal to terminate the current communica-
tion. This is used to change the mode of communication
(read, write) between the slave and master without releasing
the serial interface lines.
Serial Interface Read/Write Examples
Examples below show how serial bus cycles can be linked
together for multiple register read and write access cycles.
For sequential register accesses, each ACK handshake ini-
tiates further SCL clock cycles from the master to transfer
the next data byte.
Write to one register
1. Start signal
2. Slave Address byte (R/W bit = LOW)
3. Pointer byte
4. Data byte to base address
5. Stop signal
Write to four consecutive registers
1. Start signal
2. Slave Address byte (R/W bit = LOW)
3. Pointer byte
4. Data byte to base address
5. Data byte to (base address + 1)
6. Data byte to (base address + 2)
7. Data byte to (base address + 3)
8. Stop signal
Read from one register
1. Start signal
2. Slave Address byte (R/W bit = LOW)
3. Pointer byte (= base address)
4. Stop signal (optional)
5. Start signal
6. Slave Address byte (R/W bit = HIGH)
7. Data byte from base address
8. Stop signal
Read from four registers
1. Start signal
2. Slave Address byte (R/W bit = LOW)
3. Pointer byte (= base address)
4. Stop signal (optional)
5. Start signal
6. Slave Address byte (R/W bit = HIGH)
7. Data byte from base address
8. Data byte from (base address + 1)
9. Data byte from (base address + 2)
10. Data byte from (base address + 3)
11. Stop signal
FMS9874
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REV. 1.5 11/10/00