Maxim Integrated MAX31782 - Manual (Page 168)

MaximIntegrated 19-3
MAX31782 User’s Guide
Revision 0; 8/11
does not require a prefixing operation even though the register DP[0] is 16-bit . This is because the prefix value defaults
to zero, so the line
move PFX[0], #00h
is not required .
19.3ReadingandWritingRegisters
All functions in the MAX31782 are accessed through registers, either directly or indirectly . This section discusses load-
ing registers with immediate values and transferring values between registers of the same size and different sizes .
19.3.1Loadingan8-BitRegisterwithanImmediateValue
Any writable 8-bit register with a sub-index from 0h to 7h within its module can be loaded with an immediate value in a
single cycle using the MOVE instruction .
move AP, #05h ; load accumulator pointer register with 5 hex
Writable 8-bit registers with sub-indexes 8h and higher can be loaded with an immediate value using MOVE as well,
but an additional cycle is required to set the prefix value for the destination .
move WDCN, #33h ; assembles to: move PFX[2], #00h
; move (WDCN-80h), #33h
19.3.2Loadinga16-BitRegisterwitha16-BitImmediateValue
Any writable 16-bit register with a sub-index from 0h to 07h can be loaded with an immediate value in a single cycle if
the high byte of that immediate value is zero .
move LC[0], #0010h ; prefix defaults to zero for high byte
If the high byte of that immediate value is not zero or if the 16-bit destination sub-index is greater than 7h, an extra cycle
is required to load the prefix value for the high byte and/or the high-order register index bits .
; high byte <> #00h
move LC[0], #0110h ; assembles to: move PFX[0], #01h
; move LC[0], #10h
; destination sub-index > 7h
move A[8], #0034h ; assembles to: move PFX[2], #00h
; move (A[8]-80h), #34h
19.3.3MovingValuesBetweenRegistersoftheSameSize
Moving data between same-size registers can be done in a single-cycle MOVE if the destination register’s index is from
0h to 7h and the source register index is between 0h and Fh .
move A[0], A[8] ; copy accumulator 8 to accumulator 0
move LC[0], LC[1] ; copy loop counter 1 to loop counter 0
If the destination register’s index is greater than 7h or if the source register index is greater than Fh, prefixing is required .
move A[15], A[0] ; assembles to: move PFX[2], #00h
; move (A[15]-80h), A[0]