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Hi Bernie ,
In the VADC specific tests can be used to support functional safety claims.
Some of these signals need internal resistors to be switched into the analog input path.
As this has an influence on the signal acquisition and potentially leads to wrong values in case such a test is enabled by error, the GLOBTF register has not only a bit to enable the resistors but another bit that protects write access to the enable bit.
This mechanism only allows enabling of the test signal resistors in case the enable bit and the write access control bit are written in the same time.
An example: To enable the internal bandgap acquisition in TC23xx, of course first the signal path must be enabled by the RCEN bit. RCEN is write protected by the RCWC bit.
To change the state of RCEN, both must be written at the same time:*VADC_GLOBTF.U = (1<<31) | (1<<30);
Kind regards
Christine
In the VADC specific tests can be used to support functional safety claims.
Some of these signals need internal resistors to be switched into the analog input path.
As this has an influence on the signal acquisition and potentially leads to wrong values in case such a test is enabled by error, the GLOBTF register has not only a bit to enable the resistors but another bit that protects write access to the enable bit.
This mechanism only allows enabling of the test signal resistors in case the enable bit and the write access control bit are written in the same time.
An example: To enable the internal bandgap acquisition in TC23xx, of course first the signal path must be enabled by the RCEN bit. RCEN is write protected by the RCWC bit.
To change the state of RCEN, both must be written at the same time:*VADC_GLOBTF.U = (1<<31) | (1<<30);
Kind regards
Christine
