SPRUJ53B April 2024 – September 2024 TMS320F28P550SJ , TMS320F28P559SJ-Q1
Ping frames are one of the most basic frames that can be generated by the FSI. Table 25-6 shows the structure of the ping frames.
Idle State | Preamble | SOF | Frame Type | Frame Tag | EOF | Postamble | Idle State |
---|---|---|---|---|---|---|---|
1111 | 1001 | 0000 | xxxx | 0110 | 1111 |
The ping frame type is always 0000. The frame tag is defined by the application. Separate frame tags exist for timer and software initiated ping frames. No data or CRC is transmitted in a ping frame.
The main purpose of the ping frame is to periodically send a notification to the receiver to make sure an active connection between the transmitter and receiver. The transmitter and receiver cores implement different features to allow the ping frame to operate as a line break detect feature.
On the transmitter, the ping frame is the only frame that can be set up and transmitted without any further software or DMA intervention. Ping frames can be transmitted by any (or all) of the three sources: automatic ping timer, software, or external triggers. See Section 25.3.2.3.3 for information on how the transmitter configures and sends the ping frames.
The receiver has a ping watchdog that can detect if a ping frame has not been received in a predetermined window. This allows the receiver to know if the connection between the receiver and the transmitter has been broken. See Section 25.3.3.4 for information on how the receiver handles ping frames.