|Top Previous Next|
Listed left-to-right, top-to-bottom:
Most jumpers determine which on-board devices are connected to Cell pins. They are set at the factory so that all devices are connected. If you will be connecting Cell pins to your own devices, the jumpers allow you to disconnect the on-board devices so they will not interfere.
Pot - A0
When in place, this jumper connects the potentiometer to pin A0. This provides an easy way to apply a variable analog voltage to one of the ADC pins. The voltage from the potentiometer can be varied over the approximate range 0 - 2.5V, depending on resistor tolerance and supply voltage variations.
The Cell analog reference input Aref is connected to the high side of the potentiometer, so the 100% setting will always correspond exactly to the max ADC value if the Aref pin is selected as the analog reference voltage. Note that it is not possible to disconnect the Aref pin from this reference source.
When the PWMA module is used, the PWM outputs appear on pins B0 - B3. On the Development Kit, these pins are connected to buffers with separate output pads (PWM0 - PWM3) which allows extra drive capability. You can choose whether these buffers drive with 3.3V logic levels or 5V logic levels. The jumper should be placed across the 3.3V and DRV pins for 3.3V levels, or across the 5V and DRV pins for 5V levels.
EEPROM - B4
The Development Kit includes a 1Mb EEPROM chip to allow experimenting with the Cell SPI port. When in place, this jumper connects the EEPROM chip select to pin B4. When removed, the EEPROM chip is disabled, so although it remains connected to some of the Cell pins, it will not interfere with any other use of the pins.
LED - A6
When in place, this jumper connects one of the two green LEDs to pin A6.
LED - A5
When in place, this jumper connects one of the two green LEDs to pin A5
When this jumper and the USB Disable jumper are in place, SerialA (Cell pins C2 and C3) are connected to the RS-232 serial port. When removed and the USB Disable jumper is in place, SerialA is disconnected from any on-board device and may be driven by an external device at 3.3V logic levels.
When this jumper is in place, the USB port is disabled. The USB port will be disconnected from Cell SerialA, and it will not respond as a USB device if connected to computer. When removed, SerialA is connected to the USB port, and the USB port will respond as a Silicon Labs CP210x USB-to-serial converter -- thus SerialA will have a direct connection to the host computer.
Note that the USB port must be connected to a USB power source regardless of the setting of this jumper.