Datasheet

Analog Integrated Circuit Device Data
99 Freescale Semiconductor
MC34708
Functional Block Description
7.8.4.9 JiG Cable USB and UART
The JIG cable is used for test and development and has an ID resistance to differentiate it from a regular USB cable. The Jig
cable has 2 ID resistance values to resemble a USB JIG type1/2, and 2 ID resistance values to resemble a UART JIG type1/2
cable.
7.8.4.9.1 USB JIG Cable 1 or 2
Under normal operation, setting the control bits when the identified accessory is a USB JIG 1 or 2 cable, both the DPLUS to DP,
the DMINUS to DM switches are switched on.
When SW_HOLD = 0, the switching action of DPLUS to DP, and the DMINUS to DM switches are controlled by the WAIT bit. If
WAIT = 1, the signal switches will be turned ON after a WAIT. If WAIT = 0, the signal switches won't be turned on until the WAIT
bit is set to '1' by the SPI/I
2
C. When SW_HOLD = 1, regardless of what the WAIT is set to, '0' or '1', the signal switches are turned
on, once the USB JIG cable is identified.
The ID detector and the VBUS detector both monitor the detachment of the USB JIG cable. The ID detection circuit continues to
be ON for detachment detection in the Active mode. When the ID_FLOAT is set, the Detach bit in the Interrupt Status 0 register
is set to inform the host. When the USBDETS is set to '0', which means either the VBUS power is removed or the cable is
detached, the Detach bit is also set to inform the host. The mini USB interface moves to the Standby mode. If the Detach bit is
set, due to the removing only the VBUS or the ID resistance, and the cable is not detached completely, the identification flow will
be triggered again. The ID_FLOAT bit or USBDETS bit still indicate an accessory is connected when the mini USB interface
moves to the Standby mode. All the signal switches are turned off
7.8.4.9.2 UART JIG Cable 1 or 2
Under normal operation, setting the control bits when the identified accessory is a UART JIG cable 1 or 2, both the RxD to DP
and the TxD to DM switches are switched on.
When SW_HOLD = 0, the switching action of RxD to DP, and the TxD to DM switches, are controlled by the WAIT bit. If WAIT = 1,
the signal switches will be turned on after a WAIT time. If WAIT = 0, the signal switches won't be turned on until the WAIT bit is
set to '1' by the SPI/I
2
C. When SW_HOLD = 1, regardless of what the WAIT is set to, '0' or '1', the signal switches are turned on,
once the UART JIG cable is identified.
The ID detection comparator continues to be ON for detachment detection in the Active mode. When the ID_FLOAT is set, the
Detach bit in the Interrupt Status 0 register is set to inform the host the accessory is detached. The mini USB interface then enters
the Standby mode.
7.8.4.10 TTY Operation Mode
A TTY converter is a type of audio accessory. It has its own ID resistance. When a TTY converter is attached, this sets the TTY
bit in the USB Device Type register and the Attach interrupt bit in the Interrupt Status 0 register. During normal operation, when
setting the control bits, the automatic switch configuration of the TTY converter, is similar to that of an Audio Type 1 accessory.
The SPK_R to DP switch, and MIC to VBUS switch are turned on, but the SPK_L to DM switch can only be turned on when
TTY_SKPL bit in USB Control register is manually set to 1. In addition, the MOTG, and M0 switches are turned off to isolate the
VBUS pin.The TTY accessory doesn’t support the remote control key. The Power Save mode operation and the detachment
detection are the same as those of the Audio Type 1 device.
7.8.4.11 UART Operation Mode
During normal operation, when setting the control bits, when the identified accessory is a UART cable, both the RxD and the TxD
switches are switched on (see
Figure 30).
The ID detection comparator continues to be ON for detachment detection in the Active mode. When the ID_FLOAT is set, the
Detach bit in the USB interrupt Sense register, is set to inform the host the accessory is detached. The MC34708 USB detection
then enters Standby mode.