DSPIC33FJ64GP706 datasheet(22/322 Pages) MICROCHIP

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dsPIC33FJXXXGPX06/X08/X10

DS70286C-page 20

2.7

Oscillator Value Conditions on

Device Start-up

If the PLL of the target device is enabled and

configured for the device start-up oscillator, the

maximum oscillator source frequency must be limited

to 4 MHz < FIN < 8 MHz to comply with device PLL

start-up conditions. This means that if the external

oscillator frequency is outside this range, the

application must start-up in the FRC mode first. The

default PLL settings after a POR with an oscillator

frequency outside this range will violate the device

operating speed.

Once the device powers up, the application firmware

can initialize the PLL SFRs, CLKDIV and PLLDBF to a

suitable value, and then perform a clock switch to the

Oscillator + PLL clock source. Note that clock switching

must be enabled in the device Configuration word.

2.8

Configuration of Analog and

Digital Pins During ICSP

Operations

If MPLAB ICD 2, ICD 3 or REAL ICE 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

ADPCFG and ADPCFG2 registers.

The bits in the registers that correspond to the A/D pins

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

ICE, 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

ADPCFG and ADPCFG2 registers during initialization

of the ADC module.

When MPLAB ICD 2, ICD 3 or REAL ICE is used as a

programmer, the user application firmware must

correctly configure the ADPCFG and ADPCFG2

registers. Automatic initialization of these registers 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.

2.9

Unused I/Os

Unused I/O pins should be configured as outputs and

driven to a logic-low state.

Alternatively, connect a 1k to 10k resistor to VSS on

unused pins and drive the output to logic low.

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