MPC5xxx中的主题 Re: MPC5746R DCF calcs spreadsheet query

MPC5746R DCF calcs spreadsheet query

jamesmurray — Thu, 18 Feb 2021 15:14:54 GMT

The DCF calculation spreadsheet is a useful idea as the documentation is complex.

I've just started using it and either I'm misunderstanding something, or there are some maths errors in the sheet.

1. See attached screenshot for DCF_UTEST_Miscellaneous.
At the top, the record shows as 0x0002,8500,0100,0020 but the DCF record section shows as 0x0002,8500,0100,0024.

Looking at the "register address" calculated field it shows as 0b000000000001001 - but the final bit should be zero from the address data above. Where has that last bit=1 come from ?

2. On the STCU_clients and PASS_clients sheets, all of the parity bits are fixed at zero, they don't calculate - is there a reason for this? On the Misc sheet there is a mixture. Won't this generate invalid DCF records if the parity is not being set?

regards

James

Re: MPC5746R DCF calcs spreadsheet query

PetrS — Thu, 18 Feb 2021 20:05:57 GMT

Hi,

1) the upper value shows 64bit value concatenating data and control words (values from row 16 and 20). As Miscellaneous client has got spread address, triple voting and parity strategy (see Table 6-5 of the RM), 3 clients has to be written and value 0x1,0x2 and 0x4 must be added to its default address

that's why after adding parity and stop bits the value of first client ends with 24 and next with 2A and 30.

2) As per Table 6-5 no special strategy is considered for STCU and PASS clients and so parity is not calculated.

BR, Petr

Re: MPC5746R DCF calcs spreadsheet query

jamesmurray — Fri, 19 Feb 2021 14:33:32 GMT

Good information. Thanks. I have some further questions about specific values relating to the security features. I'll raise a ticket for that instead.

James