TSC2102

Informations about the hardware interface between the i.MXL and the TSC2102.

Introduction

This chip is a "SMART" 4-Wire Touch Screen Controller with Stereo DAC and HP Amplifier. It is used on the DevFull board but any good electronician should be able to add it to it's DevLight. It is although possible to solder this chip directly on your LQ043 adapter board, if you have one.

Hardware interface with the i.MXL

Touchscreen

Configuration and data exchange is done through the SPI bus n°2 (SPI2).
The SPI 2 port is shared with the LCD interface of the i.MXL (these signals are present on the DevLight V2 LCD connector).

Audio

Configuration is done through SPI2 bus and audio data exchange through SSIA

Signals

i.MXL/DevLight	TSC2102	Functionnality
SPI2_SCLK/REV	SCLK	SPI clock
SPI2_TXD/SPL_SPR	MOSI	SPI MasterOut SlaveIn
SPI2_RXD_1/PS	MISO	SPI MasterIn SlaveOut
PortB 17/SSI1_TXDAT	SSn	SPI Chip select
SPI2_SS/PortD 8/CLS	PINT/DAVn	Interrupt
Reset (on Reset switch)	RESETn	Global reset signal

Remark:

• i.MXL/DevLight SPI Chip Select signals are not used by Linux SPI infrastructure; it needs multiple chip select (one for each chip connected on the bus), and so GPIOs are used for that purpose.
• Chip interrupt is on Port D because Port B has already some and interrupt are shared on the same port.

Drivers

• TSC2102 Linux driver details

Self-made adapter board

For those who would like to test this component before the DevFull release, take a look at this link: http://www.farnell.fr and type '1426186' as part to search.
This is a small pcb converting a tssop32 to two rows of 2.54mm holes...

ssi test tool

Use special release of tsc2102 driver and imxssi for audio development purpose. available under buildroot menuconfig/hardwarehandling

• Requirements:

TSC2102 mclk: 16MHZ
FS rate: 32KHz

• uboot: Enable register debug from u-boot:

BIOS> mw.l 0x00200008 0
BIOS> mw.l 0x00210008 0

• linux: Load spi/tsc drivers

modprobe spi_imx
modprobe tsc2102

• imxssi: generate ssi signal

Special release of imxssi can generate an audio signal.
just use imxssi with three parameters:

# imxregs param1 param2 param3

param1 can be 0: triangular signal or 1: sinusoïdal signal.
param2: period of the signal in number of samples per channel.
param3: Signal level coefficient [0.0 .. 1.0].

For example to produce a 300Hz 5v(pk-pk) sinusoid:

# imxssi 1 50 0.15

• next step: dma transfer

Links

• TSC2102 Web page at Texas Instruments

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