A6 GPRS/GSM Shield
Crowtail- Base Shield for Raspberry Pi
This is a Crowtail base shield for Raspberry Pi with UART/I2C/Analog/Digital interface. All the Crowtail modules can be plugged onto Raspberry Pi through this base shield. Moreover, this shield has an on-board ADC chip so that analog output modules can be used on Raspberry Pi. The ADC chip used is MCP3008. It talks to Raspberry Pi using SPI interface.