Pad Connections

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Making Pad Connections

Important! Do not drive any Cell input with logic levels greater than 3.3V.


All pads are on 0.1" grid, making it easy to add pin headers for the desired connections. For example, a single 24-pin strip could be used for the entire column of pads encompassing PortA, PortB, SerialA, and I2C.


Prototyping area

This is a grid of unconnected pads to allow additional components to be mounted and connected.


Cell I2C pins

The pads SDA and SCL connect to the I2C pins of the Cell, also called the two-wire interface. SDA refers to serial data and SCL to serial clock. Both pins have 4.7k pull-ups on board, but additional external pull-ups are allowed if needed for higher data rates and/or longer cable runs.


The on-board LM73 temperature sensor and MCP4728 4-channel DAC are permanently connected to these pins. The LM73 is at I2C address 0x92; the MCP4728 is at I2C address 0xC0. Refer to their individual data sheets for information on communicating with these devices.


Cell SerialA pins

The pads RxD and TxD connect to the SerialA pins of the Cell. RxD refers to receive data (input) and TxD to transmit data (output). To use these pins, the USB Disable jumper should be in place and the RS-232 Enable jumper should be removed. This will prevent the RxD pin from being driven by either the on-board USB device or the on-board RS-232 driver.


Cell PortB pins

The pads B0 - B7 provide direct connection to the corresponding pins of the Cell. These pins can be set up in various combinations of digital I/O, PWM, serial ports, and SPI port - see the Cell documentation for more information.


Cell PortA pins

The pads A0 - A7 provide direct connection to the corresponding pins of the Cell. These pins can be individually set up as digital I/O or analog input - see the Cell documentation for more information.


On-board DAC outputs

The pads DAC-A to DAC-D connect to the analog outputs of the on-board MCP4728 4-channel digital-to-analog converter.


Cell DAC output

The DAC pad connects to the analog output of the Cell.


Buffered PWM outputs

The pads PWM0 - PWM3 are buffered versions of B0 - B3, which are the outputs pins for PWMA. The PWM Drive jumper is used to set the drive level to 3.3V or 5V. There are three pads associated with each output: the buffered output (left), a +5V source (middle), and ground (right). This 3-pin layout matches the pinout of a standard R/C servo.