STMPE812ABJR STMicroelectronics, STMPE812ABJR Datasheet - Page 32

• Manufacturer Part Number: STMPE812ABJR
• Description: Touch Screen Converters & Controllers Touchscreen cntrlr S-Touch
• Manufacturer: STMicroelectronics
• Type: Resistive Touch Controllersr

Specifications of STMPE812ABJR

• Rohs: yes
• Input Type: 1 TSC
• Data Rate: 400 kbps
• Resolution: 12 bit
• Interface Type: 4-wire, I2C
• Supply Voltage: 1.65 V to 3.6 V
• Supply Current: 100 uA
• Operating Temperature: - 40 C to + 85 C
• Package / Case: CSP-12
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Supply Voltage - Max: 3.6 V
• Supply Voltage - Min: 1.65 V

Touchscreen controller
11.1
11.2
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Touchscreen controller detection sequence
Following is the sequence of detection in the STMPE812A touchscreen controller for X, Y
and Z:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10. Drive X
11. Wait for settling time
12. Measure X
13. Stop drive
14. Touch detect
3 modes of acquisition
1.
The host system selects a “sampling period” with, based on internal timer, the touchscreen
controller takes a complete set of samples on every period. The host system may choose to
read the data by:
2.
As and when sampling is desired, host writes to the ACQ bit and:
3.
The host sets the internal timer for the desired data-rate. On staring the touchscreen
controller in this mode, a complete set of sample is taken immediately. The touchscreen
controller enters in hibernate mode (clock is turned OFF, only monitors the PEN-DOWN
status). When system host reads the Touch Data available in FIFO, another set of data is
taken immediately.
Touch detect
Drive Y
Wait for settling time
Measure Y
Stop drive
Drive Z
Wait for settling time
Measure Z
Stop drive
Data acquisition timed by internal timer:
–
–
–
Data acquisition triggered by a write to “ACQ” bit:
–
–
–
Data acquisition using host-controlled sampling rate control
Waiting for the INT
Polling for INT_STATUS register for TOUCH DATA
Reading the TSC_DATA at approximately the same timing. (Use “Data Valid Status
Read” option in this mode)
Poll the ACQ to wait for completion
Wait for INT for Touch Data access
Poll the FIFO after approximate time required for sampling. (Use “Data Valid
Status Read” option in this mode)
Doc ID 18225 Rev 4
STMPE812A