MC34708 datasheet(99/159 Pages) FREESCALE

99 / 159 page

Analog Integrated Circuit Device Data



Freescale Semiconductor

MC34708

Functional Block Description

7.8.4.8

Audio Type 1 Operation Mode

Audio Type 1 accessories have the same interface shown in Figure 27, either stereo or mono, with or without a remote control,

or with or without a microphone. When a device, such as a microphone is not connected to the accessory, the corresponding pin

in the mini-USB connector will be left floating. With the normal operation setting of the control bits, the accessory is identified as

an Audio Type 1 device, the analog switches SW4 and SW7 for SPK_R to DP, SPK_L to DM, and SW5 for VBUS to MIC are

turned on, and the MOTG, and M0 switches are turned off, to isolate the VBUS pin.

The MC34708 supports the remote control key for an Audio Type 1 device. If the RAW DATA = 0, the ADC is turned on

periodically to monitor the ID line change caused by the key press. The period is programmed by the Device Wake-up bits. If the

ADC Result changes, the ADC_Change bit in the USB Interrupt Sense register is set to inform the baseband. If the RAW

DATA = 1, a comparator is enabled to monitor the key press. The timing of the key press when RAW DATA = 1 is shown in

Figure 28. If a key is pressed for a time less than 20 ms, the MC34708 ignores it. If the key is still pressed after 20 ms, the

MC34708 starts a timer to count the time during which the key is kept pressed. There are three conditions according to the press

time: Error key press, short key press, and long key press.

1. Error key press: if the key press time is less than TKP, the Error bit in the USB Button register and the short key press bit

KP in USB Interrupt Sense register are set to indicate that an error happens. The Error bit is reset to '0' when the USB

Button register is read or the next key press happens. The KP bit is cleared when the Interrupt 1 register is read.

2. Short key press: if the key press time is between TKP and TLKP, the KP bit and the corresponding button bit in USB

Button are set to inform the baseband. If the ADC result is not one of the ADC values of the 13 buttons, the Unknown bit in

the Button 2 register is set. The INT pin is driven high when the key is released and returns to low when the interrupt

3. Long key press: if the key press time is longer than TLKP, the long key press bit LKP in the USB Interrupt Sense register,

and the corresponding button bit, are set to inform the baseband. If the ADC Result is not one of the ADC values of the 13

buttons, the Unknown bit in the USB Button register is set. When the key is released, the long key release bit LKR in the

Interrupt 2 register is set to interrupt the baseband again.

Figure 27. Audio Accessory with Remote Control and Microphone

Table 93. Switch Configuration When Controlled by the Device Type Register

Device Type

Audio

USB

UART

USB CHG

Dedicated CHG

On SW#

4, 5, 7

3, 6,

1, 2

3, 6

Off SW

MOTG, M0

(67)

Device Type

5WT1 CHG

5WT2 CHG

JIG_USB_ON

JIG_USB_OFF

JIG_UART_ON

JIG_UART

TTY

On SW#

3, 6

4, 5, 7

Off SW

(67)

MOTG, M0

Notes

67.

Switches M0, M1, and MOTG are controlled by software by the OTGEN and VUSBSEL bits.

MC34708 数据表(PDF) 99 Page - Freescale Semiconductor, Inc

MC34708 数据表(HTML) 99 Page - Freescale Semiconductor, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

数据表下载