The WebCell has 20 I/O pins that can be configured in various combinations of the following:

  • 16 general-purpose I/O pins
  • 8 analog inputs
  • 3 serial ports
  • 1 SPI port
  • 1 I2C port
  • 2 pulse-width modulation (PWM) modules with 4 channels each
  • 4 capture inputs that measure frequency and/or pulse width

In addition, there is a dedicated analog output.

Special I/O Features

General-purpose I/O – Each pin can be individually configured as an input or output; direction can be changed on the fly. Inputs can optionally enable an internal pullup resistor.

Analog inputs – The analog-to-digital converter (ADC) allows choice of several voltage references, including a dedicated pin (shared with DAC) or an internal precision voltage. Conversions require only 16µs and give an 11-bit result.

Serial ports – An extremely flexible baud rate generator can achieve any rate up to 1Mb/s with 1% accuracy. All serial I/O is internally buffered both transmitting and receiving.

SPI port – Data rates up to 15Mb/s are possible. Multiple devices can be connected to the SPI bus, each with their own slave select (SS) pin. Three-wire devices (shared input/output line) can be used.

PWM – Each module can be set to its own frequency. For servo control, frequency can be set as low as 60Hz. For motor and other power control applications, frequencies as high as 40kHz still have 1% resolution.

Input capture – Any 4 general-purpose I/O pins can be measured for pulse width or period with 2µs resolution.

Analog output – the digital-to-analog converter (DAC) allows choice of several voltage references, including a dedicated pin (shared with ADC) or an internal precision voltage.


Connection to the network is through a 10 Base-T Ethernet jack. The WebCell can be assigned an IP address dynamically (DHCP), or it can be assigned a static IP. It sets its internal clock automatically (SNTP client).

The WebCell includes an FTP server for transferring files to and from the microSD card. It also has the ability to send email (SMTP client), which is useful as an alert in a monitoring application.


The WebCell circuit board measures 2.5” x 1.2” with mounting holes in the corners. Connections are made through a 2 x 17 array of pads on 0.1” centers compatible with a standard 34-pin dual-row header.