Atmel Evaluation Kit AT91SAM9G25-EK AT91SAM9G25-EK Data Sheet

947

SAM9G25 [DATASHEET]

11032D–ATARM–10-Mar-2014

The Software Modem Device (SMD) is a block for communication via a modem's Digital Isolation Barrier (DIB) with a 
complementary Line Side Device (HLSD).

SMD and HLSD are two parts of the "Transformer only" solution. The transformer is the only component connecting SMD 
and HLSD. The transformer is used for power, clock and data transfers. Power and clock are supplied by the SMD and 
consumed by the HLSD. The data flow is bidirectional. The data transfer is based on pulse width modulation for 
transmission from the SMD to the HLSD, and for receiving from the HLSD.

There are two channels embedded into the protocol of the DIB link: 



Data channel, 



Control channel. 

Each channel is bidirectional. 

The data channel is used to transfer digitized signal samples at a constant rate of 16 bits at 16 kHz. 

The control channel is used to communicate with control registers of the HLSD at a maximum rate of 8 bits at 16 kHz. 

The SMD performs all protocol-related data conversion for transmission and received data interpretation in both data and 
control channels of the link.

The SMD incorporates both RX and TX FIFOs, available through the DMAC interface. Each FIFO is able to hold eight 32-
bit words (equivalent to 16 modem data samples).