12-bit ADC

Originally, MotoHawk defined all ADC outputs as being 10 bits. The 0 : 1023 ADC output range is consistent across all Woodward MCS control modules, through MotoHawk 2009b releases.

The 5xx and S12 processors have 10-bit ADCs.

The MPC 55xx microprocessors (ECM-5554-112, ECM-5544-112..) have 12-bit ADCs, but with the specific circuitry involved, they are only truly accurate to 10-bit resolution, and Freescale indicates 10 bit accuracy is targeted for the sampling rate we configure on this module. All conversions are 12-bit, and then re-mapped to the 0 : 1024 scale and saturated at 1023 as a default 10-bit setting.

Starting with MotoHawk 2010a releases, the Analog Input and Analog Input Reference blocks will offer up to 12-bit ADC results on any module, but the 55xx-based and S12X-based modules might have non-meaningful data in those lower bits. However, you can access exactly what the converter outputs.

The 5xx-based and S12-based modules will pad the lower bits with zeros.

Note that changing to 12 bit ADC will impact the scaling of that input.