SPRUIZ1B July 2023 – August 2024 TMS320F28P650DH , TMS320F28P650DK , TMS320F28P650SH , TMS320F28P650SK , TMS320F28P659DH-Q1 , TMS320F28P659DK-Q1 , TMS320F28P659SH-Q1
The FSI module in this device supports multi-node TDM configurations, whereas a single main device can control multiple remote node devices. To use the FSI module in the multi-node TDM configuration described, the remote node device must utilize tag matching and user data filtering.
This multi-node TDM configuration is supported in the FSI module through time-division multiplexing. When TDM is enabled, each remote node device must also have tag matching enabled. Figure 27-10 shows a scheme where a single main device is communicating with multiple remote node devices. All FSI receive modules in the remote node devices are directly connected to the main device transmit module. The transmit modules of the remote node devices are chained serially such that each transmit module is connected to the next remote node device and the last remote node device output connects to the main device receive module. Each remote node device decides, based on the received frame's tag, whether to transmit the data or to enter bypass mode where the previous remote node device transmit module directly connects to the next remote node device. This is done by using the FSI transmit module TDM_IN.
When an FSI transmitter module is used in TDM mode, TXCLK_TDM_IN, TXD0_TDM_IN and TXD1_TDM_IN pins are used if the transmitter is required to enter bypass mode. Figure 27-11 shows how the FSI module operates when in multi-node TDM mode.
The SEL_TDM_PATH signal is sourced from the CLB module. The CLB module also generates the transmit trigger for the FSI transmitter. The CLB module must be configured to decide when to generate the FSI transmit trigger based on the status of the data, ping, and frame tag match generated by the FSI receiver module. The FSITX module must be configured to transmit on an external trigger and the corresponding CLB trigger input must be selected. In a broadcast scenario (FSI tag match notifies all remote node devices that a match has occurred), the CLB module inside each remote node device generates a trigger and SEL_TDM_PATH signal. The main key here is that the trigger and the SEL_TDM_PATH signal must be generated at a different time interval in a non-overlapping manner. Figure 27-12 shows an example of FSI transmit triggers and the multi-node TDM SEL_TDM_PATH signals generated by the RX_TRIGx signal or the CLB module of the remote node devices in a broadcast scenario.
The TXCLK_TDM_IN, TXD0_TDM_IN, and TXD1_TDM_IN for the FSI transmit modules available in this device are shown in Table 27-11.
FSI Transmit Module | TXCLK_TDM_IN | TXD0_TDM_IN | TXD1_TDM_IN |
---|---|---|---|
FSITXA | FSIRXB RXCLK | FSIRXB RXD0 | FSIRXB RXD1 |
FSITXB | FSIRXA RXCLK | FSIRXA RXD0 | FSIRXA RXD1 |
The FSI transmit modules are configured to use the external triggers generated by the CLB to initiate the transmission. Through appropriate configurations, the logic is designed to work assuming that only one TDM trigger is generated until the transmission is completed. In the case where there is another trigger before the current transmission is competed, an error is flagged in the TX_EVT_ERR_STATUS register. Figure 27-13 shows the connections between CLB, FSITX, and FSIRX modules.
In Figure 27-10, the main device is connected to three remote node devices. The main device uses FSITXA to transmit frames to the three remote node devices. Each remote node device receives every frame, using the FSIRXA. The remote node devices are chained together using the FSITXA output and FSIRXB inputs (configured as FSITXA TDM input). When a remote node device receives a frame using the FSIRXA, the device checks the tag of the frame to see if the tag matches the specified reference value in the tag compare register. When a match does occur, the CLB module configures the FSITXA of the remote node device to select the local FSITXA outputs as the source for the output pins. However, if a match does not occur, the FSITXA of the remote node device is configured to enter bypass mode. There, the device selects the FSITXA TDM inputs (which is FSIRXB) to be passed on to the output pins.
In this case, when a frame is transmitted by the main device and the frame tag is matched only in one of the remote node devices, all other devices with non-matching tags enter the bypass mode to allow the main device to receive frames from the chosen remote node device.