OM6281 NXP Semiconductors, OM6281 Datasheet - Page 10

• Manufacturer Part Number: OM6281
• Description: DAUGHTER CARD PCA9698 FOR OM6275
• Manufacturer: NXP Semiconductors

Specifications of OM6281

• Main Purpose: Interface, GPIO Expander
• Embedded: No
• Utilized Ic / Part: OM6275, PCA9698
• Primary Attributes: 40-Bit 40-Port GPIO Expander
• Secondary Attributes: I²C Interface
• Interface Type: I2C
• For Use With/related Products: PCA9698
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

NXP Semiconductors
9. Application specific: LED blinking and dimming with the PCA9530 and
UM10267_1
User manual
the PCA9698
8.2.1 Polling mode
8.2.2 Interrupt mode
8.2 GPIO input
9.1 Theory of operation
In polling mode, the host controller must read the input port registers at predetermined
intervals to check if an input has changed. Depending on the application, the interrupt
mode described in
state on the input pins.
In interrupt mode the interrupt pin is toggled to signal the host controller when an input
change of state has been detected. The interrupt mask register specifies which signal is
allowed to generate an interrupt.
The PCA9698 has the capability to drive up to 40 LEDs (within certain power restrictions
on the package, which can be overcome with the use of FETs). To enhance the
application of the PCA9698, a PCA9530 can be used to drive the Output Enable (OE) pin
to blink and dim the output of the LEDs. A pattern with intermediate complexity can be
easily generated by combining the outputs of the PCA9530.
A 74LVC1G38GW NAND gate is used to demonstrate the OE polarity inversion (active
HIGH instead of default active LOW) of the PCA9698.
1. Select Bank0 and verify that the default values are displayed.
2. Since the PCA9698 has a small pull-up on the I/O, a read on the Input Port 0 register
3. Pull Port0.7 to a logic LOW.
4. Read the Input Port 0 register and verify that the Input Port 0 register reads 0x7F.
1. Select Bank1 and verify the default values are active.
2. Un-check the MSK7 and MSK6 bits in the Mask Interrupt 1 register.
3. With the aid of an external pull-down, pull Port1.6 and Port1.7 bits to a logic LOW.
4. Verify the INT light is illuminated on the board.
5. Toggle the MSK6 and MSK7 bits and verify the INT light goes off only when both bits
6. Read the Input Port 1 register and verify the contents is now 0x3F and the INT light is
7. Pull the IO1.7 signal HIGH and verify that the interrupt light is on.
8. Toggle the MSK6 bit and verify that the INT light remains on.
9. Read the Input Port 1 register and verify that the contents is 0xBF and the INT light is
returns 0xFF.
are masked.
off.
off.
Section 8.2.2
Rev. 01 — 24 September 2008
may be a more efficient method of verifying changes of
PCA9698 demonstration board OM6281
UM10267
© NXP B.V. 2008. All rights reserved.
10 of 16