Freescale Semiconductor M9328MX21ADSE user manual Touchscreen ADC, Ethernet Interface

Configuration and Operation

i.MX21

BA1..3

D0..15

CS_LAN

B_OE

B_RW B_DQM3_EB3 UART3_RTS

VCC

CS8900A-CQ3Z
SA8	Isolation
SA9
	Transformer
SA0
			P9
SA4..7
SA10..19
SA1..3		RJ45 Connector
D0..15

AEN

IOR

IOW

SBHE

INTRQ0

CHIPSEL

Figure 2-8. Ethernet Interface

2.3.7Touchscreen ADC

The ADS is equipped with an Analog Devices AD7873BRQZ ADC. The ADC communicates with the touchscreen of the LCD on the Base board. Variable resistor VR1 on the Base board can be used to change the VBAT input voltage to the ADC. The i.MX21 communicates with the ADC via the CSPI1 interface. Setting S1-7 to ON connects CSPI1_SS0 to the ADC chip select. Setting S1-8 to ON connects the ADC interrupt out to UART3_CTS. Figure 2-9shows the ADC interface.

i.MX21	S1
	AD7873BRQZ
	8
UART3_CTS	PENIRQ VREF
	7	VBAT
CSPI1_SS0	CS
		X+
CSPI1_SCLK	DCLK	Y+
CSPI1_MISO	DOUT	X-
CSPI1_MOSI	DIN	Y-

VCC

VR1

P7

LCD CONNECTOR

Figure 2-9. ADC Interface

	M9328MX21ADSE User’s Manual, Rev. A
2-8	Freescale Semiconductor