TSC2117 datasheet(79/192 Pages) TI

79 / 192 page

TSC2117

Low-Power Audio Codec With Embedded miniDSP, Stereo Class-D

Speaker Amplifier, and Smart Four-Wire Touch-Screen Controller

www.ti.com

SLAS550A – APRIL 2009 – REVISED JUNE 2009

Figure 5-46. Circular Buffer

Converted data is automatically written into the FIFO. To control the writing, reading and interrupt process,

a write pointer (WRPTR), a read pointer (RDPTR), and a trigger pointer (TGPTR) are used. The read

pointer always shows the location that is read next. The write pointer indicates the location in which the

next converted data is to be written. The trigger pointer indicates the location at which an interrupt is

generated if the write pointer reaches that location. Trigger level is the number of the data values needed

to be present in the FIFO before generating an interrupt. For example, in X–Y continuous-scan mode with

trigger level set to 8, the TSC2117 generates an interrupt after writing (X1, Y1), (X2, Y2), (X3, Y3), (X4,

Y4), i.e., four data-pairs or eight data values. Figure 5-46 shows the case when the trigger level is

programmed as 32. On resetting the buffer mode, RDPTR moves to location 1, WRPTR moves to location

1, and TGPTR moves to a location equal to the programmed trigger level.

The user can select the input or input sequence to be converted by writing to page 3/register 3,

bits D5–D2. The converted values are written in a predefined sequence to the circular buffer. The user has

flexibility to program a specific trigger level in order to choose the configuration which best fits the

application. When the number of converted data values written in FIFO becomes equal to the

programmed trigger level, then the device generates an interrupt signal on GPIO1 or GPIO2. In buffer

mode, the user should program this pin as Data Available. In buffer mode, touch-screen-related

conversions (X, Y, Z1, Z2) are allowed only in self-controlled mode and nontouch-screen-related

conversions (VBAT, AUX1, AUX2, TEMP1, TEMP2) are allowed only in host-controlled mode.

Buffer mode can be used in single-shot conversion or continuous-conversion mode.

In single-shot conversion mode, once the number of data values written reaches the programmed trigger

level, the TSC2117 generates an interrupt and waits for the user to start reading. As soon as the user

starts reading the first data value from the last converted set, the TSC2117 clears the interrupt and starts

a new set of conversions, and the trigger pointer is incremented by the programmed trigger level. An

interrupt is generated again when the trigger condition is satisfied.

In continuous-conversion mode, once the number of data values written reaches the programmed trigger

level, the TSC2117 generates an interrupt. It immediately starts a new set of conversions, and the trigger

pointer is incremented by the programmed trigger level. An interrupt is cleared either by writing the next

converted data value into the FIFO or by starting to read from the FIFO.

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TSC2117 Datasheet(PDF) 79 Page - Texas Instruments