KIT34825EPEVME Evaluation Board
, Rev. 2.0
Freescale Semiconductor
21
Using the Evaluation Kit
6.2.2
USB Port
Connect the evaluation kit to a PC using a regular USB A-to-mini-B cable. Since a USB port has a 5V on
the VBUS pin, the D+ and D- not shorted, and the ID pin floating, the 34825 recognizes the accessory as
a USB port. The identification result is displayed in the GUI software. The internal power MOSFET is
turned on automatically to switch the 5V VBUS to the OUT pin. The I2C host leave the ISET output high
impedance so only the OUT indication LED will be turned on. The PC will recognize the flash memory
connected to the evaluation board and the user can read from or write to the flash memory the same way
as if the flash memory is attached to a USB port of the PC directly. Try to copy a large file to see the data
transfer speed.
If a second PC is not available, the user can use the same PC shown in
6.2.3
USB Charger
A USB charger is a special charger defined in the
USB Charging Specification
Version 1.0 from the USB
developer’s forum. If such a charger is not available, one can use the on-board accessory simulator with
the following two steps, starting with the default jumper configuration.
1. Short J3.
2. Short J9.
Once J9 is shorted, an accessory recognition flow starts in the 34825 and a USB charger is recognized.
The internal power MOSFET is turned on automatically and ISET is set to low by the I2C host. Both OUT
and ISET LED indications are turned on.
6.2.4
Audio Accessory
If the user has an additional audio accessory (a stereo headphone with a microphone and the 5-button
remote control), as described in section 4.4. Please refer to
for the construction of the audio
accessory.
When attached to the mini-USB connector, the audio accessory is recognized by the 34825 and the
Identification Result in the GUI shows “Audio R/C”, representing an audio accessory with remote control.
The signal connections between the accessory and the baseband system (simulated by the PC in this
case) are established. Any music out from the PC will be passed to the stereo headphone while the
microphone signal from the headset will be passed to the PC. The cell phone window in the GUI shows
a volume indication, the playback progress bar, and a red-dot button for recording the voice (refer to
section 5.3.8 for more details).
The 5 buttons in the remote control are assigned to the play/pause, previous, next, volume up, and
volume down functions in the media player. When the Play/Pause is pressed, the PC starts to play music
to the headphone. One can play with all five buttons to find out the functions. Try to press quickly and
press and hold the key for a few seconds to see the color difference in the key displays of the GUI
software.
The voice recording function is for demonstrating that the headset has independent stereo audio and the
microphone channels. When the record button is clicked, the voice is recorded into the PC through the
microphone in the headset. Clicking the record button again will stop recording and immediately start
playing back recorded voice, while the stereo music continues to play independently.
The user can also use the J1 to simulate all 13 keys, as described in section 4.2.
