CY7C65013
CY7C65113
Document #: 38-08002 Rev. *B
Page 29 of 51
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Refer to Sections 9.1 and 9.2 for more information of setting GPIO interrupt polarity and enabling individual GPIO interrupts. If
one port pin has triggered an interrupt, no other port pins can cause a GPIO interrupt until that port pin has returned to its inactive
(non-trigger) state or its corresponding port interrupt enable bit is cleared. The USB Controller does not assign interrupt priority
to different port pins and the Port Interrupt Enable Registers are not cleared during the interrupt acknowledge process.
14.8
I2C Interrupt
The I2C interrupt occurs after various events on the I2C-compatible bus to signal the need for firmware interaction. This generally
involves reading the I2C Status and Control Register (Figure 12-2) to determine the cause of the interrupt, loading/reading the
I2C Data Register as appropriate, and finally writing the Processor Status and Control Register (Figure 13-1) to initiate the
subsequent transaction. The interrupt indicates that status bits are stable and it is safe to read and write the I2C registers. Refer
to Section 12.0 for details on the I2C registers.
When enabled, the I2C-compatible state machines generate interrupts on completion of the following conditions. The referenced
bits are in the I2C Status and Control Register.
1. In slave receive mode, after the slave receives a byte of data: The Addr bit is set, if this is the first byte since a start or restart
signal was sent by the external master. Firmware must read or write the data register as necessary, then set the ACK, Xmit
MODE, and Continue/Busy bits appropriately for the next byte.
2. In slave receive mode, after a stop bit is detected: The Received Stop bit is set, if the stop bit follows a slave receive transaction
where the ACK bit was cleared to 0, no stop bit detection occurs.
3. In slave transmit mode, after the slave transmits a byte of data: The ACK bit indicates if the master that requested the byte
acknowledged the byte. If more bytes are to be sent, firmware writes the next byte into the Data Register and then sets the
Xmit MODE and Continue/Busy bits as required.
4. In master transmit mode, after the master sends a byte of data. Firmware should load the Data Register if necessary, and
set the Xmit MODE, MSTR MODE, and Continue/Busy bits appropriately. Clearing the MSTR MODE bit issues a stop signal
to the I2C-compatible bus and return to the idle state.
5. In master receive mode, after the master receives a byte of data: Firmware should read the data and set the ACK and
Continue/Busy bits appropriately for the next byte. Clearing the MSTR MODE bit at the same time causes the master state
machine to issue a stop signal to the I2C-compatible bus and leave the I2C-compatible hardware in the idle state.
6. When the master loses arbitration: This condition clears the MSTR MODE bit and sets the ARB Lost/Restart bit immediately
and then waits for a stop signal on the I2C-compatible bus to generate the interrupt.
The Continue/Busy bit is cleared by hardware prior to interrupt conditions 1 to 4. Once the Data Register has been read or written,
firmware should configure the other control bits and set the Continue/Busy bit for subsequent transactions. Following an interrupt
from master mode, firmware should perform only one write to the Status and Control Register that sets the Continue/Busy bit,
without checking the value of the Continue/Busy bit. The Busy bit may otherwise be active and I2C register contents may be
changed by the hardware during the transaction, until the I2C interrupt occurs.
Figure 14-4. GPIO Interrupt Structure
Port
Register
OR Gate
GPIO Interrupt
Flip Flop
CLR
GPIO
Pin
1 = Enable
0 = Disable
Port Interrupt
Enable Register
1 = Enable
0 = Disable
Interrupt
Priority
Encoder
IRQout
Interrupt
Vector
D
Q
M
U
X
1
(1 input per
GPIO pin)
Global
GPIO Interrupt
Enable
(Bit 5, Register 0x20)
IRA
Configuration
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