OM6279,598 NXP Semiconductors, OM6279,598 Datasheet - Page 11

• Manufacturer Part Number: OM6279,598
• Description: DEMO BOARD LED DIMMER
• Manufacturer: NXP Semiconductors

Specifications of OM6279,598

• Main Purpose: Lighting, RGB LED Controller
• Embedded: Yes, MCU, 8-Bit
• Utilized Ic / Part: PCA9564PW, PCA9555PW, PCA9531PW, PCA9533DP/01
• Primary Attributes: I2C Bus Controller, 1 8-Bit GPIO, 1 8-Bit LED Dimmer
• Secondary Attributes: Different Demonstration Programs Through MCU
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• Other names: 568-4003; 935283363598

Philips Semiconductors
9397 750 14062
Application note
4.3.1 How the keypad control works
4.3.2 Keypad mapping with the PCA9555 I/Os
4.3 Dialing routine
Keypad control is done using a PCA9555 with its INT signal connected to a GPIO of the
P89LV51RD2 microcontroller. The 16 keys of the keypad are simply connected to the
16 GPIOs of the PCA9555 and to the ground, without any other external components
since internal 100 kΩ pull-ups are provided by the PCA9555.
Each time one (or more) key is pressed, the PCA9555 generates an Interrupt that is
detected by the P89LV51RD2. A read of the input port registers of the PCA9555 is then
initiated in order to determine which key(s) has (have) been pushed. Two modes are
possible:
Code is described in the function called ‘GPIO_Interrupt_Handler()’ described in
5.3
When an Interrupt is detected, the P89LV51RD2 initiates 2 input port register readings. A
delay between the 2 readings allows:
The delay is long enough so that if 2 readings are identical, it assumes that a continuous
push is applied to the pushbutton. If the second reading is different, it assumes that the
user released the pushbutton. The delay is also short enough so that a push in another
key is not masked.
A variable called ‘GPIO_Polling_On’ enable/disables the polling option thus making the
scan suitable for a ‘one shot’ detection.
Continuous push detection is enabled when set to ‘1’.
Table 2:
Table 3:
1. One time only pushed detection: only one read is performed.
2. Continuous push detection: the P89LV51RD2 keeps polling the input port registers as
•
•
Bit 7
Bit 7
“I2C_Routines.c”.
long as the register content is different from 0xFF (meaning that at least one key is
pushed).
potential switch bounces to be filtered.
Detection of a one time or continuous push detection.
F2
8
PCA9555 Input port Register 0
PCA9555 Input port Register 1
Bit 6
Bit 6
F1
7
Rev. 01 — 7 January 2005
Bit 5
Bit 5
END
6
Bit 4
Bit 4
SND
5
Bit 3
Bit 3
4
#
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
Bit 2
Bit 2
3
*
LED dimmer demoboard
AN10315
Bit 1
Bit 1
2
0
Section
Bit 0
Bit 0
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