6.10 Transmitter - Digital Section

The digital part of the transmitter is a mirror of the receiver. The settings controlled the ISO Control register (0x01) are applied to the transmitter just like the receiver. In the TRF7962A default mode (ISO Mode), the TRF7962A automatically adds all the special signals like start of communication, end of communication, SOF, EOF, parity bits and CRC bytes.

The data is then coded to modulation pulse levels and sent to the RF output stage modulation control unit. Just like with the receiver, this means that the external system MCU only must load the FIFO with data and all the microcoding is done automatically, again saving the firmware developer code space and time. Additionally, all the registers used for transmit parameter control are automatically preset to optimum values when a new selection is entered into the ISO Control register (0x01).

There are two ways to start the transmit operation:

• Send the transmit command and the number of bytes to be transmitted first, and then start to send the data to the FIFO. The transmission starts when first data byte is written into the FIFO.
• Load the number of bytes to be sent into registers 0x1D and 0x1E and load the data to be sent into the FIFO (address 0x1F), followed by sending a transmit command (see Direct Commands section). The transmission then starts when the transmit command is received.

At the end of a transmit operation, the external system MCU is notified by interrupt request (IRQ) with a flag in the IRQ register (0x0C) indicating TX is complete (example value = 0x80).