PIC24F04KA201 datasheet(20/224 Pages) MICROCHIP

20 / 224 page

PIC24F04KA201 FAMILY

DS39937B-page 18

Preliminary

2.6

External Oscillator Pins

Many microcontrollers have options for at least two

oscillators: a high-frequency primary oscillator and a

low-frequency

secondary

oscillator

(refer

Section 8.0 “Oscillator Configuration”

for details).

The oscillator circuit should be placed on the same

side of the board as the device. Place the oscillator

circuit close to the respective oscillator pins with no

more than 0.5 inch (12 mm) between the circuit

components and the pins. The load capacitors should

be placed next to the oscillator itself, on the same side

of the board.

Use a grounded copper pour around the oscillator

circuit to isolate it from surrounding circuits. The

grounded copper pour should be routed directly to the

MCU ground. Do not run any signal traces or power

traces inside the ground pour. Also, if using a

two-sided board, avoid any traces on the other side of

the board where the crystal is placed. A suggested

layout is shown in Figure 2-4.

For additional information and design guidance on

oscillator circuits, please refer to these Microchip

Application Notes, available at the corporate web site

(www.microchip.com):

• AN826, “Crystal Oscillator Basics and Crystal

Selection for rfPIC™ and PICmicro® Devices”

• AN849, “Basic PICmicro® Oscillator Design”

• AN943, “Practical PICmicro® Oscillator Analysis

and Design”

• AN949, “Making Your Oscillator Work”

FIGURE 2-4:

SUGGESTED PLACEMENT

OF THE OSCILLATOR

CIRCUIT

2.7

Configuration of Analog and

Digital Pins During ICSP

Operations

If the MPLAB ICD 2, ICD 3 or REAL ICE emulator is

selected as a debugger, it automatically initializes all of

the A/D input pins (ANx) as “digital” pins by setting all

bits in the AD1PCFGL register.

The bits in this register that correspond to the A/D pins

that are initialized by the MPLAB ICD 2, ICD 3 or REAL

ICE emulator must not be cleared by the user

application firmware; otherwise, communication errors

will result between the debugger and the device.

If your application needs to use certain A/D pins as

analog input pins during the debug session, the user

application must clear the corresponding bits in the

AD1PCFGL register during initialization of the ADC

module.

When the MPLAB ICD 2, ICD 3 or REAL ICE emulator

is used as a programmer, the user application firmware

must correctly configure the AD1PCFGL register.

Automatic initialization of this register is only done

during debugger operation. Failure to correctly

configure the register(s) will result in all A/D pins being

recognized as analog input pins, resulting in the port

value being read as a logic ‘0’, which may affect user

application functionality.

2.8

Unused I/Os

Unused I/O pins should be configured as outputs and

driven to a logic low state. Alternatively, connect a 1 kΩ

to 10 kΩ resistor to VSS on unused pins and drive the

output to logic low.

Main Oscillator

Guard Ring

Guard Trace

Secondary

Oscillator

PIC24F04KA201 Datasheet(PDF) 20 Page - Microchip Technology

PIC24F04KA201 Datasheet(HTML) 20 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL