tA2D_Channels Defines which A/D channels to use.
Depending on the processor configuration, the format may change (refer to the datasheet):
If there is ANSEL/ANSELH or equivalent registers, this is directly their ANx mask (BYTE or WORD).
If there is an ADCON1.PCFG (PIC18), this is the code that defines a predefined digital / analog mapping
tA2D_Mode = (adm8bit, admfull); Defines the acquisition result format, 8-bit or full size right justified. The result of the acquisition is always right justified in a byte (8-bit), a word (unsigned 16-bit, full size) or an integer (signed 16-bit, full size). For backward compatibility, old symbols are declared as deprecated: adm8bits = adm8bit and adm10bit = admfull.
tA2D_ACQT Defines the acquisition time possibilities. For PIC18 it maps to the TAD code, for others it is the nb of microseconds to wait after a channel change before to start the conversion (BYTE).
For PIC18, they are in the form adtTAD_n where n is the nb of required TAD. The type may vary according to the processor's possibilities.
tA2D_Clock Defines the A/D clock possibilities. They may be of the form adcFOSCn where n is the Fosc divider, or adcFrc for RC mode.
tA2D_Vref_Mode Defines the Vref mode possibilities. They may be of the form advPmMm, whre Pm is the Vref+ mode and Mm is the Vref- mode. Common mode is advVddVss, or advVdd for the simplest devices.