Vault 7: Projects
This publication series is about specific projects related to the Vault 7 main publication.
PIC24F Family Reference Manual
DS39712D-page 7-16 © 2011 Microchip Technology Inc.
7.14.1 POR and Long Oscillator Start-up Times
The oscillator start-up circuitry and its associated delay timers are not linked to the device Reset
delays that occur at power-up. Some crystal circuits (especially low-frequency crystals) will have
a relatively long start-up time. Therefore, one or more of the following conditions is possible after
SYSRST
is released:
• The oscillator circuit has not begun to oscillate.
• The Oscillator Start-up Timer has NOT expired (if a crystal oscillator is used).
• The PLL has not achieved a lock (if PLL is used).
The device will not begin to execute code until a valid clock source has been released to the
system. Therefore, the oscillator and PLL start-up delays must be considered when the Reset
delay time must be known.
7.14.2 Examples of Device Start-up Sequences
Figure 7-5 through Figure 7-8 depict graphical sequences for the delays associated with device
Reset for several operating scenarios. The individual delays are characterized in Section 7.16
“Electrical Specifications”.
Figure 7-5 displays the delay time line when a crystal oscillator is used as the system clock. The
internal POR pulse occurs at the V
POR threshold. TPOR, TSTARTUP and TRST delays occur after
the internal POR pulse.
Figure 7-5: Device Reset Delay, Crystal (XT/HS/SOSC) Clock Source
POR Circuit Threshold Voltage
SYSRST
(1)
Internal Power-on Reset Pulse
TPOR
(2)
TOST
(5)
VDD
Oscillator Released to System
POR
System Reset Released
Note 1: Delay times shown are not drawn to scale.
2: T
POR = Power-on Reset delay.
3: T
STARTUP = TVREG if the on-chip regulator is enabled or TPWRT if it is disabled.
4: T
RST = Internal State Reset time.
5: T
OST = Oscillator Start-up Timer (OST). A 10-bit counter counts 1024 oscillator periods before releasing the
oscillator clock to the system.
OSC Delay
(1)
TSTARTUP
(3)
TRST
(4)
Protego_Release_01_05-Related-OEM-Documentation-PIC24FJ32MC10X-Reference_Manual_Section7-Reset.pdf