AN246 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'AN246' PDF : 13 Pages View PDF
Conclusion
AN2466
2.8
Power-Up sequence
1. The GND pin of the device should be grounded first. First ground the GND pin.
2. The Reset_N pin should be connected to VIO through a weak pull-up resistor. Connect
the Reset_N pin to VIO through a weak pull-up resistor.
3. The I2C lines, SCL and SDATA should be connected to the host. Connect the I2C lines,
SCL and SDATA to the host. Both lines should have pull-up resistors to VCC.
4. The ADDRESS pin should be connected to GND or VCC as per slave address chosen.
Connect the ADRESS pin to GND or VCC according to the slave address chosen. This
can also be accomplished by using external weak pull-up and pull-down resistors on
those two pins or by driving directly from the host.
5. Both VCC and VIO should be supplied through suitable decoupling capacitors.
6. The INT pin should be pulled high to VIO through a weak pull-up resistor. Pull the INT
pin high to VIO through a weak pull-up resistor.
7. With these minimal connections, the device functions in normal mode providing I2C
access to the internal registers. All GPIOs are in default input mode.
● Tips for hardware trouble shooting:
If the device does not function at the end of the power-up sequence provided above, the
following tips can be used for troubleshooting.
1. All pins are provided with an internal reverse biased ESD protection diode to GND. The
connectivity of the pins vs. GND can be verified.
2. I2C clock frequency can be reduced or increased to observe the corresponding change
in the current consumption of the device. If there is no change, the device connections
should be verified again.
3
Conclusion
The STMPE801 is a very versatile device that can be used to reduce the load on the CPU
and expand the number of IOs available for the processor. The small size and simple
configuration makes it a very attractive proposition for high-end, portable applications like
smart phones. This application note provided the setup information to interface this device
to a digital engine. The GPIOs in STMPE801 can also be used to perform special functions
like key-pad matrix scanning by using suitable software keypad controller routines on the
host processor. (Refer also application note AN2421: Using the STMPE801 as a keypad
controller)
4
Revision history
Table 9. Revision history
Date
Revision
23-Mar-2007
1
Initial release
Changes
12/13
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