Introduction
12.1 Introduction
The touchscreen controller and analog-to-digital converter subsystem (TSC_ADC_SS) is an 8-channel
general-purpose analog-to-digital converter (ADC) with optional support for interleaving touchscreen (TS)
conversions for a 4-wire, 5-wire, or 8-wire resistive panel. The TSC_ADC_SS can be configured for use in
one of the following applications:
•
8 general-purpose ADC channels
•
4-wire TSC with 4 general-purpose ADC channels
•
5-wire TSC with 3 general-purpose ADC channels
•
8-wire TSC
12.1.1 TSC_ADC Features
The main features of the TSC_ADC_SS include:
•
Support for 4-wire, 5-wire, and 8-wire resistive TS panels
•
Support for interleaving TS capture and general-purpose ADC modes
•
Programmable FSM sequencer that supports 16 steps:
–
Software register bit for start of conversion
–
Optional start of conversion HW synchronized to Pen touch or external HW event (but not both)
–
Single conversion (one-shot)
–
Continuous conversions
–
Sequence through all input channels based on a mask
–
Programmable OpenDelay before sampling each channel
–
Programmable sampling delay for each channel
–
Programmable averaging of input samples - 16/8/4/2/1
–
Differential or singled ended mode setting for each channel
–
Store data in either of two FIFO groups
–
Option to encode channel number with data
–
Support for servicing FIFOs via DMA or CPU
–
Programmable DMA Request event (for each FIFO)
–
Dynamically enable or disable channel inputs during operation
–
Stop bit to end conversion
•
Support for the following interrupts and status, with masking:
–
Interrupt for HW pen (touch) event
–
Interrupt for HW Pen Up event
–
Interrupt after a sequence of conversions (all non-masked channels)
–
Interrupt for FIFO threshold levels
–
Interrupt if sampled data is out of a programmable range
–
Interrupt for FIFO overflow and underflow conditions
–
Status bit to indicate if ADC is busy converting
12.1.2 Unsupported TSC_ADC_SS Features
This device supports all TSC_ADC_SS features.
1023
SPRUH73H – October 2011 – Revised April 2013
Touchscreen Controller
Copyright © 2011–2013, Texas Instruments Incorporated