NXP Semiconductors PCA9665 - Manual (Page 51)

PCA9665_2 © NXP B.V. 2006. All rights reserved.
Product data sheet Rev. 02 — 7 December 2006 51 of 91
NXP Semiconductors
PCA9665
Fm+ parallel bus to I 2 C-bus controller
– the SCL line is held LOW by the PCA9665 after the 2 bytes have been sent
– the PCA9665 sends an Interrupt, sets SI = 1 and updates I2CSTA register
– I2CSTA reads 28h
5. Program I2CCOUNT = 40h (64 bytes to read and Last byte acknowledged).
6. Load I2CDAT with A1h (I 2 C-bus slave address and Read command).
7. Program I2CCON with STA = 1, SI = 0, MODE = 1.
– the PCA9665 sends a ReSTART command
– an interrupt is asserted and the I2CSTA register is updated
– the I2CSTA register reads 10h
8. Program I2CCON with STA = STO = SI = 0, MODE = 1.
– address A1h is sent followed by a read of 64 data bytes
– the last data byte is acknowledged
– the SCL line is held LOW by the PCA9665 after the data is read
– the PCA9665 sends an interrupt and updates I2CSTA register
– I2CSTA reads 50h
9. The microcontroller reads the 64 data bytes from the PCA9665.
10. Program I2CCOUNT = C0h (64 bytes and Last byte is not acknowledged).
11. Program I2CCON with STA = STO = SI = 0, MODE = 1.
12. The PCA9665 reads 64 bytes and does not acknowledge the last byte.
– the PCA9665 sends an Interrupt and updates I2CSTA register
– the I2CSTA reads 58h
– the SCL line is held LOW by the PCA9665
– the slave should release the SDA line
13. The microcontroller reads the 64 bytes from the PCA9665.
14. Program I2CCON with SI = STA = 0, ST0 = 1, MODE = X.
– the PCA9665 sends a STOP condition
– no interrupt is generated by the PCA9665
– the I2CSTA register contains F8h
8.6 I2CCOUNT register
When a write to the I2CCOUNT register is requested, the buffer pointer is reset and points
at the first byte. Loading of the data in the I2CDAT buffer then starts at the first byte.
Once an operation has been performed (SI = 1 and an interrupt is generated), the
I2CCOUNT register contains the number of bytes that have been received (Receiver
mode) or the number of bytes that have been sent (Transmitter mode). See
Table 42 for
more information.
In Buffered Transmitter mode, the first byte that is sent to the I 2 C-bus is always the first
byte that has been loaded in the I2CDAT buffer.