Freescale Semiconductor M9328MX21ADSE user manual CD Quality Codec, Keypad, Audio Connectors

Configuration and Operation

2.3.8CD Quality CODEC

The ADS has a Wolfson WM8731SEDS 32-bit linear low power stereo CODEC with a built-in headphone driver (U24). The CODEC is controlled by the i.MX21, which sends the digital audio data via an SSI2 interface and control data via an I2C interface.

The CODEC has stereo line and mono microphone level audio inputs as well as stereo headphone outputs. It features a mute function, programmable line level volume control, and a bias voltage output suitable for an electret type microphone. Table 2-5shows the CODEC connectors and describes their basic functions.

Table 2-5. Audio Connectors

Connector	Descriptions
P10	Stereo line in jack
P11	Dynamic microphone input jack
P12	Headphone jack for audio out

The WM8731SEDS data sheet is available at http://www.wolfsonmicro.com/

2.3.9Keypad

The ADS includes an external keypad module that connects to the Base board. The keys provide tactile feedback. The i.MX21 keypad interface reads the pad via the KCOL[5:0] and KROW[5:0] signals. the interface has chording diodes to prevent ghost key presses. The keys are labeled with numeric, cursor control, soft key, and spare key functions, but the actual functionality is determined by user software. The default keypad can be replaced by a custom design. The UART2 signals that are multiplexed internally with the KCOL[7,6] and KROW[7,6] signals are brought out to keypad connector P5. This allows the use of an 8x8 keypad matrix. Table 2-6shows the key switch connections to the keypad signals by function name (as labeled on the PCB) and the switch reference designators.

Table 2-6. Keypad Layout and Connections

	KCOL5	KCOL4	KCOL3	KCOL2	KCOL1	KCOL0
KROW5	APP1	SEND	KEY 1	UP	KEY 2	END
	SW1	SW2	SW3	SW4	SW5	SW6
KROW4	APP2	HOME	LEFT	ACTION	RIGHT	BACK
	SW7	SW8	SW9	SW10	SW11	SW12
KROW3	DOWN	APP3	1 -	2 ABC	3 DEF	EXTRA 2
	SW13	SW14	SW15	SW16	SW17	SW18
KROW2	VOL UP	APP4	4 GHI	5 JKL	6 MNO	EXTRA 3
	SW19	SW20	SW21	SW22	SW23	SW24
KROW1	VOL DOWN	EXTRA 1	7 PQRS	8 TUV	9 WXYZ	EXTRA 4
	SW25	SW26	SW27	SW28	SW29	SW30
KROW0	POWER	RECORD	*	0 +	#	EXTRA 5
	SW31	SW32	SW33	SW34	SW35	SW36

	M9328MX21ADSE User’s Manual, Rev. A
Freescale Semiconductor	2-9