PIC16LF18854 Datasheet, PDF (17/668 Pages) Microchip Technology – C Compiler Optimized RISC Architecture

PIC16(L)F18856/76
1.1 Register and Bit naming
conventions
1.1.1 REGISTER NAMES
When there are multiple instances of the same
peripheral in a device, the peripheral control registers
will be depicted as the concatenation of a peripheral
identifier, peripheral instance, and control identifier.
The control registers section will show just one
instance of all the register names with an ‘x’ in the place
of the peripheral instance number. This naming
convention may also be applied to peripherals when
there is only one instance of that peripheral in the
device to maintain compatibility with other devices in
the family that contain more than one.
1.1.2 BIT NAMES
There are two variants for bit names:
• Short name: Bit function abbreviation
• Long name: Peripheral abbreviation + short name
1.1.2.1 Short Bit Names
Short bit names are an abbreviation for the bit function.
For example, some peripherals are enabled with the
EN bit. The bit names shown in the registers are the
short name variant.
Short bit names are useful when accessing bits in C
programs. The general format for accessing bits by the
short name is RegisterNamebits.ShortName. For
example, the enable bit, EN, in the COG1CON0 regis-
ter can be set in C programs with the instruction
COG1CON0bits.EN = 1.
Short names are generally not useful in assembly
programs because the same name may be used by
different peripherals in different bit positions. When this
occurs, during the include file generation, all instances
of that short bit name are appended with an underscore
plus the name of the register in which the bit resides to
avoid naming contentions.
1.1.2.2 Long Bit Names
Long bit names are constructed by adding a peripheral
abbreviation prefix to the short name. The prefix is
unique to the peripheral thereby making every long bit
name unique. The long bit name for the COG1 enable
bit is the COG1 prefix, G1, appended with the enable
bit short name, EN, resulting in the unique bit name
G1EN.
Long bit names are useful in both C and assembly pro-
grams. For example, in C the COG1CON0 enable bit
can be set with the G1EN = 1 instruction. In assembly,
this bit can be set with the BSF COG1CON0,G1EN
instruction.
1.1.2.3 Bit Fields
Bit fields are two or more adjacent bits in the same
register. Bit fields adhere only to the short bit naming
convention. For example, the three Least Significant
bits of the COG1CON0 register contain the mode
control bits. The short name for this field is MD. There
is no long bit name variant. Bit field access is only
possible in C programs. The following example
demonstrates a C program instruction for setting the
COG1 to the Push-Pull mode:
COG1CON0bits.MD = 0x5;
Individual bits in a bit field can also be accessed with
long and short bit names. Each bit is the field name
appended with the number of the bit position within the
field. For example, the Most Significant mode bit has
the short bit name MD2 and the long bit name is
G1MD2. The following two examples demonstrate
assembly program sequences for setting the COG1 to
Push-Pull mode:
Example 1:
MOVLW ~(1<<G1MD1)
ANDWF COG1CON0,F
MOVLW 1<<G1MD2 | 1<<G1MD0
IORWF COG1CON0,F
Example 2:
BSF COG1CON0,G1MD2
BCF COG1CON0,G1MD1
BSF COG1CON0,G1MD0
1.1.3
REGISTER AND BIT NAMING
EXCEPTIONS
1.1.3.1 Status, Interrupt, and Mirror Bits
Status, interrupt enables, interrupt flags, and mirror bits
are contained in registers that span more than one
peripheral. In these cases, the bit name shown is
unique so there is no prefix or short name variant.
1.1.3.2 Legacy Peripherals
There are some peripherals that do not strictly adhere
to these naming conventions. Peripherals that have
existed for many years and are present in almost every
device are the exceptions. These exceptions were
necessary to limit the adverse impact of the new
conventions on legacy code. Peripherals that do
adhere to the new convention will include a table in the
registers section indicating the long name prefix for
each peripheral instance. Peripherals that fall into the
exception category will not have this table. These
peripherals include, but are not limited to, the following:
• EUSART
• MSSP
 2016 Microchip Technology Inc.
Preliminary
DS40001824A-page 17