HI.
I'm currently using an AFE sampling system with MC33665A and MC33774 to form a double-chain loopback structure. The MC33665A's PORT0 and PORT1 are configured as MADD0 and MADD1 respectively, and all commands are currently sent via MADD0. When I only connect the daisy chain between PORT0 and DC1, my communication is normal. However, when I also connect the daisy chain between PORT1 and DC2, I find that the 33774 cannot reply with a response frame. Why is this? I have confirmed that the PORT configuration of the 33665 is correct and that SYS_TPL_CFG.RESPCFG in the 33774 is set to 00 SAME mode.
I am currently using an AFE sampling system consisting of the MC33665A + MC33774 in a dual-ring loop configuration. I have configured PORT0 and PORT1 of the MC33665A as MADD0 and MADD1, respectively, and all commands are currently sent through MADD0.
When I connect only the daisy chain between PORT0 and DC1, communication works correctly. However, after I also connect the daisy chain between PORT1 and DC2, the MC33774 no longer responds when I send requests to it.
Why does this happen?
I have read back and verified that the MC33665 PORT configuration is correct, and I have configured SYS_TPL_CFG.RESPCFG = 00 (SAME mode) in the MC33774.
HI.
1. I want to know if it is necessary to reverse the allocation of DADD from the position where MADD=1?
2. My current SYS_PORT0_CFG configuration is TIMEOUT=0, CADD=1, MADD=0, PROTOCOL=1, ALLCHAINS=1, TERM=1, RX=1, EN=1
SYS_PORT1_CFG is configured with TIMEOUT=0, CADD=1, MADD=1, PROTOCOL=1, ALLCHAINS=1, TERM=1, RX=1, EN=1
Hello,
According to the AN13910 TPL Loopback Recommendation, when two MC33665A TPL ports are connected as a loopback ring, there are several configuration requirements that may cause the behavior you are seeing.
For a loopback configuration:
- We recommend assigning device addresses (DADD) in ascending order from one side of the ring and in reverse order from the loopback side (I do not see this in your image).
- If two ports are connected as loopback, one of the ports should have SYS_PORTx_CFG[RX] = 0 to avoid duplicate data entering the MC33665 buffer.
- In addition, one of the ports should have SYS_PORTx_CFG[ALLCHAINS] = 0. If both loopback ports accept ALLCHAINS commands, document states that this can cause signal conflicts and communication errors.
Could you please share the values of SYS_PORT0_CFG and SYS_PORT1_CFG (especially EN, RX, ALLCHAINS, MADD, and CADD)? That would help determine whether the loopback ports are configured according to the AN13910 recommendations.
Hello,
According to AN13910 TPL Loopback Recommendation, the DADD assignment should be reversed from the MADD=1 side in a loopback topology.
In addition, your current configuration has RX=1 and ALLCHAINS=1 on both ports. For a loopback connection, we recommend disabling RX and ALLCHAINS on one of the ports to avoid duplicate routing and communication conflicts.
Could you please try configuring one port with RX=0 and ALLCHAINS=0 (for example, PORT1) and verify whether the MC33774 starts returning response frames?