PIC18F46K22-I/MV Microchip Technology, PIC18F46K22-I/MV Datasheet - Page 71

• Manufacturer Part Number: PIC18F46K22-I/MV
• Description: 64KB, Flash, 3968bytes-RAM,8-bit Family,nanoWatt XLP 40 UQFN 5x5x0.5mm TUBE
• Manufacturer: Microchip Technology
• Series: PIC® XLP™ 18Fr

Specifications of PIC18F46K22-I/MV

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 64MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, HLVD, POR, PWM, WDT
• Number Of I /o: 35
• Program Memory Size: 64KB (32K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 3.8K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 30x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 40-UFQFN Exposed Pad
• Processor Series: PIC18F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 4 KB
• Number Of Programmable I/os: 36
• Number Of Timers: 3 x 8-bit. 4 x 16-bit
• Operating Supply Voltage: 1.8 V to 5.5 V
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

A CALL type instruction causes a push onto the stack;
the Stack Pointer is first incremented and the location
pointed to by the Stack Pointer is written with the
contents of the PC (already pointing to the instruction
following the CALL). A RETURN type instruction causes
a pop from the stack; the contents of the location
pointed to by the STKPTR are transferred to the PC
and then the Stack Pointer is decremented.
The Stack Pointer is initialized to ‘00000’ after all
Resets. There is no RAM associated with the location
corresponding to a Stack Pointer value of ‘00000’; this
is only a Reset value. Status bits indicate if the stack is
full or has overflowed or has underflowed.
FIGURE 5-2:
5.1.2.2
The STKPTR register
Pointer value, the STKFUL (stack full) Status bit and
the STKUNF (Stack Underflow) Status bits. The value
of the Stack Pointer can be 0 through 31. The Stack
Pointer increments before values are pushed onto the
stack and decrements after values are popped off the
stack. On Reset, the Stack Pointer value will be zero.
The user may read and write the Stack Pointer value.
This feature can be used by a Real-Time Operating
System (RTOS) for return stack maintenance.
After the PC is pushed onto the stack 31 times (without
popping any values off the stack), the STKFUL bit is
set. The STKFUL bit is cleared by software or by a
POR.
The action that takes place when the stack becomes
full depends on the state of the STVREN (Stack Over-
flow Reset Enable) Configuration bit. (Refer to
Section 24.1 “Configuration Bits”
the device Configuration bits.) If STVREN is set
(default), the 31st push will push the (PC + 2) value
onto the stack, set the STKFUL bit and reset the
device. The STKFUL bit will remain set and the Stack
Pointer will be set to zero.
 2010 Microchip Technology Inc.
Return Stack Pointer (STKPTR)
TOSU
00h
Top-of-Stack Registers
(Register
RETURN ADDRESS STACK AND ASSOCIATED REGISTERS
TOSH
1Ah
5-1) contains the Stack
for a description of
TOSL
34h
Top-of-Stack
Return Address Stack <20:0>
Preliminary
001A34h
000D58h
5.1.2.1
Only the top of the return address stack (TOS) is readable
and writable. A set of three registers, TOSU:TOSH:TOSL,
hold the contents of the stack location pointed to by the
STKPTR register
implement a software stack if necessary. After a CALL,
RCALL or interrupt, the software can read the pushed
value by reading the TOSU:TOSH:TOSL registers. These
values can be placed on a user defined software stack. At
return time, the software can return these values to
TOSU:TOSH:TOSL and do a return.
The user must disable the Global Interrupt Enable (GIE)
bits while accessing the stack to prevent inadvertent
stack corruption.
If STVREN is cleared, the STKFUL bit will be set on the
31st push and the Stack Pointer will increment to 31.
Any additional pushes will not overwrite the 31
and STKPTR will remain at 31.
When the stack has been popped enough times to
unload the stack, the next pop will return a value of zero
to the PC and sets the STKUNF bit, while the Stack
Pointer remains at zero. The STKUNF bit will remain
set until cleared by software or until a POR occurs.
Note:
PIC18(L)F2X/4XK22
11111
11110
11101
00011
00010
00001
00000
Returning a value of zero to the PC on an
underflow has the effect of vectoring the
program to the Reset vector, where the
stack conditions can be verified and
appropriate actions can be taken. This is
not the same as a Reset, as the contents
of the SFRs are not affected.
Top-of-Stack Access
(Figure
5-2). This allows users to
Stack Pointer
STKPTR<4:0>
00010
DS41412D-page 71
st
push