ia3513 integration, ia3513 Datasheet - Page 26

• Manufacturer Part Number: ia3513
• Description: Headset Voice And Power Solution
• Manufacturer: integration

Application Example 1 - Push Button Handling
The following example depicts the configuration and instruction set to handle two push buttons.
Receive (DA) channel volume UP/DOWN buttons are used in the example.
Configuration
The GPIOs used in this example are 3, 4 and 5.
GPIOs 3 and 4 are configured as CMOS inputs, with sticky mode enabled. This is done by setting the bits GPD3 and GPD4 of
register 12 to ‘0’ for input direction, and the bits GST3 and GST4 of register 15 to ‘1’ in order to enable the sticky mode. The bits
GPC3 and GPC4 of register 14 must be set to ‘0’ also.
After the previous configurations are made, in order to clear any previous events on the inputs, a ‘0’ should be written to bits
GPS3 and GPS4 of register 11. This way GPIOS 3 and 4 status bits are cleared, and set to trigger when the inputs change from
’0’ to ‘1’, which is compatible with the external pull downs implemented with resistors R1 and R2.
The interruption mask is set for GPIOS 3 and 4 by setting bits GI3 and GI4 of register 16. This will avoid the need for the host to
be constantly reading the GPIO status as it can be notified by an interruption.
To enable the interruption notification through GPIO5, the bit GIN5 of register 13 must be set to ‘1’ and the direction of this GPIO
must be set to output by setting bit GPD5 of register 12 to ‘1’.
Operation
When the UP button is pushed, node A is pulled high. This transition will be detected by GPIO4, which will set the correspondent
status bit (GPS4) of register 11 to ‘1’. As this GPIO is set to sticky mode, this value will be kept even when the button is
depressed.
The change in GPS4 will trigger an interruption because GPIO4 was selected in the interruption mask; this interruption will be
notified by GPIO5 which was selected for the interruption notification. The host will detect the interruption request, and read the
contents of the GPIO status register.
The status register when read will have the GPS4 bit equal to ‘1’, triggering the volume up action event. Then the host will
perform the associated action to pressing this button (e.g. write the receive channel gain register).
This next step is optional and can be used if after detecting that the button was pressed, there is also the need to detect when
the button is released. For this to be possible, the bit GPC4 of register 14 must first be set to ‘1’ after the press action is
detected. Afterwards the interrupt and push notification (sticky bit) of GPIO4 must be cleared by writing a ‘0’ to the bits INT and
GPS4 of register 11. Now the interrupt is set to trigger when the push button is released. When this happens GPIO5 will notify a
new interruption, and the GPS4 will read ‘1’ indicating that the GPIO4 has changed from ‘1’ to ‘0’ (due to the complementary
mode being on). The host can then perform the associated action to releasing this button, and then should clear the GPC4 on
register 14 (disable complementary mode).
To finalize the push button handling, the host acknowledges the interruption and the GPIO4 push/release notification by writing
a ‘0’ to the bits INT and GPS4 of register 11, thus clearing the interruption and the sticky bit value. Then the whole cycle can be
restarted.
The operation of the DWN button is analogous.
R1
A
UP
R2
B
DWN
GPIO4
GPIO3
LIZ
GPIO5
SCL
SDA
INT
HOST
IA3513
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