UM0851 datasheet(174/245 Pages) STMICROELECTRONICS

Part #	UM0851

Description	SPEAr is a family of highly customizable ARM-based embedded

PDF	245 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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Human interface device (HID) drivers

UM0851

174/245

Doc ID 16604 Rev 2

Human interface device (HID) drivers

This section groups all drivers related to SPEAr human interface devices.

7.1

Touchscreen driver

7.1.1

Hardware overview

There is no dedicated Touchscreen controller in SPEAr. Instead, a combination of ADC and

GPIO functions are used for Touchscreen operation. ADC channels 5 and 6 are used to

read the X and Y-coordinates respectively. By pulling GPIO high or low the device-driver

selects either ADC Channel 5 or 6.

Figure 45.

Interfacing between CLCD panel and SPEAr

7.1.2

Software overview

The touchscreen device driver reads all the touch related value from the ADC channels and

provides all the necessary functions for the application via the standard Linux Input Device

Layer Interface. The overall touchscreen software system architecture is represented in the

Figure 46.

SPEAr

CLCD panel

ADC channel 5

ADC channel 6

GPIO pin

(product specific)

UM0851 Datasheet(PDF) 174 Page - STMicroelectronics