Enum BankStyle
The MCP28XXX family has an address mapping concept for accessing registers. This provides a way to easily address registers by group or type. This is only relevant for 16-bit devices where it has two banks (Port A and B) of 8-bit GPIO pins.
public enum BankStyleFields
Separated = 1This mode keeps the two 8-bit banks registers separate.
While this keeps the register addresses for bank A the same as the 8-bit controllers it requires sending a separate command sequence to set all 16-bits as the second bank's register addresses are not sequential.
Changing IOCON.SEQOP to 1 (not the default) will cause the register address pointer to toggle between Port A and B for the given register if in this mode.
This is IOCON.BANK = 1.
Sequential = 0This mode is used specifically for 16-bit devices where it treats the two 8-bit banks as one 16-bit bank.
Each of the registers are interleaved so that sending two bytes in a row will set the equivalent register for the second bank. This way you can set all 16 GPIO pins/settings with one command sequence.
Note that this behavior is also dependent on the default behavior of IOCON.SEQOP = 0 (the default) which automatically increments the register address as bytes come in.
This is IOCON.BANK = 0 and is the default.