STMPE812ABJR STMicroelectronics, STMPE812ABJR Datasheet - Page 39

• 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

STMPE812A
11.4
Note:
Programming model
Below are steps to configure the Touchscreen controller in 3 different acquisition modes.
A. Autonomous touchscreen controller, 100 Hz, lowest power possible
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If one set of data is available in buffer, and not accessed by the I
timer is up for the next data, the STMPE812A samples the next data as scheduled.
If old data is still NOT accessed when new data is ready to be written to the buffer, it is over-
written.
If old data is IN PROGRESS of being accessed, new data is DISCARDED.
If I
LOCATION, the existing data is CONSIDERED READ, and new data ready to be written into
buffer
B. Non-autonomous touchscreen controller style-interrupt, 100Hz, lowest
power possible:
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C. Host-controlled sampling rate (lowest bus utilization)
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C host accessed PART OF the data, and moved on to read ANY OTHER REGISTER
Initialize the touchscreen controller (choose ACQ_Mode ‘00’ - data acquisition timed by
internal timer)
Initialize interrupt (with TSC_Data enabled, normal interrupt mode)
Wait for interrupt
On interrupt: Read interrupt status (this clears the set bits too)
If data is available, read data.
Initialize TSC (Choose ACQ_Mode ‘01’ - Data acquisition triggered by a write to “ACQ”
bit)
Initialize Interrupt (With TSC_Data, TSC_Touch enabled, PEN_DOWN interrupt mode)
Wait for Interrupt
On Interrupt: Read Interrupt Status (this clears the set bits too)
If PEN_DOWN, start SYSTEM_TIMER (10 ms typically)
On TIMEOUT, write ACQ bit to start acquisition
Poll interrupt status register or ACQ bit to check for acquisition status
ON issuing ACQ, 812 may assume that data in buffer is already accessed by I2C host,
and reset the relevant pointers.
Initialize TSC (choose ACQ_Mode ‘10’ - Data acquisition using host-controlled
sampling rate control)
Initialize interrupt (with TSC_Data, TSC_Touch enabled, PEN_DOWN interrupt mode)
Wait for Interrupt
On interrupt: Read Interrupt Status (this clears the set bits too)
If PEN_DOWN, start SYSTEM_TIMER (10 ms typically)
On TIMEOUT, read data
Doc ID 18225 Rev 4
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C host, yet the sampling
Touchscreen controller
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