EP9315-CB Cirrus Logic Inc, EP9315-CB Datasheet - Page 742

• Manufacturer Part Number: EP9315-CB
• Description: IC ARM920T MCU 200MHZ 352-PBGA
• Manufacturer: Cirrus Logic Inc
• Series: EP9r

Specifications of EP9315-CB

• Core Processor: ARM9
• Core Size: 16/32-Bit
• Speed: 200MHz
• Connectivity: EBI/EMI, EIDE, Ethernet, I²C, IrDA, Keypad/Touchscreen, PCMCIA, SPI, UART/USART, USB
• Peripherals: AC'97, DMA, I&sup2:S, LCD, LED, MaverickKey, POR, PWM, WDT
• Number Of I /o: 16
• Program Memory Type: ROMless
• Ram Size: 32K x 8
• Voltage - Supply (vcc/vdd): 1.65 V ~ 3.6 V
• Data Converters: A/D 8x12b
• Oscillator Type: External
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 352-BGA
• Processor Series: EP93xx
• Core: ARM920T
• Data Bus Width: 32 bit
• 3rd Party Development Tools: MDK-ARM, RL-ARM, ULINK2
• Development Tools By Supplier: EDB9315A-Z
• For Use With: 598-1144 - KIT DEVELOPMENT EP9315 ARM9
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Program Memory Size: -
• Lead Free Status / Rohs Status: No
• Other names: 598-1261

25
25-4
Analog Touch Screen Interface
EP93xx User’s Guide
25.2.1 Touch Screen Scanning: Four-wire and Eight-wire Operation
Figure 25-2
TSDetect, TSDischarge, TSXSample, and TSYSample are derived from the switch positions
in the diagram. These values are listed in
The left most part of the diagram shows how the switches are driven to detect a touch press.
This configuration is controlled by the TSDetect register.
The second part of the diagram shows all lines of the touch screen switched to ground for
discharging as controlled by the TSDischarge register.
The third example shows a voltage driven across the X-axis with the A / D sample input
connected to both Y-axis lines and the A / D referenced to the SX feedback lines as
controlled by the TSXSample register.
The right most part of the diagram shows a voltage driven across the Y-axis with the A / D
sample input connected to both X-axis lines and the A / D referenced to the SY feedback
lines for digitization as controlled by the TSYSample register.
Each time the analog switching configuration is changed, an appropriate time interval must
be provided for the circuit to stabilize due to the touch screen capacitance, and any EMI
filtering provided on the signals. This is controlled by the DLY field in the TSSetup register.
The analog touch screen interface circuitry is internally connected to a signed 12-bit analog-
to-digital converter. The 12-bit digital result is held stable until another sample is requested.
The controller reads the digital value by issuing a read pulse. This read pulse signal from the
controller is also used as a convert command for the analog-to-digital converter to begin
conversion of its next sample. The output of the ADC is a signed value. For the comparison
functions of the touch controller to work correctly, the TSSetup2.SIGND bit should be set.
The flow chart in
input on a touch screen. The ARM Core must load all of the setup registers for the touch
Table 25-1. Switch Definitions and Logical Safeguards to Prevent Physical Damage (Continued)
Bit 18
Bit 19
Bit 20
Bit 21
Bit 22
Bit 23
Bit 24
Bit 25
Bit 26
Bit 27
Bit 28
Bit 29
Bit 30
shows control for an 8-wire analog resistive touch screen. The register values
Figure 25-4
VBAT ADC input
TOUCH_PRES
S gate
DAC
sX+
sY+
sX-
sY-
sY-
X+
Y+
X+
Y+
Y-
demonstrates the sample process used for determining touch
Copyright 2007 Cirrus Logic
Pull-up to AVDD
Pull-up to AVDD
Load Resistor
Touch_Press
ADC REF+
ADC REF+
NAND gate
ADC REF-
ADC REF-
ADC input
AGND
AVDD
AVDD
AVDD
Table
SW19 = HIGH and SW11 = LOW and SW0 = LOW
SW20 = HIGH and SW13 = LOW and SW2 = LOW
SW21 = HIGH and SW14 = LOW and SW3 = LOW
25-2.
Also gates PRSTn for measuring battery with load
(SW0 = LOW or the bus SW[7-0] = 0x01)
(SW2 = LOW or the bus SW[7-0] = 0x04)
SW22 = HIGH and SW11 = LOW and
SW23 = HIGH and SW13 = LOW and
Gates input to prevent oscillations
DAC to ADC feedback test switch
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DS785UM1