upd70f3422gj-gae-qs-ax Renesas Electronics Corporation., upd70f3422gj-gae-qs-ax Datasheet - Page 134

• Manufacturer Part Number: upd70f3422gj-gae-qs-ax
• Description: 32-bit Single-chip Microcontroller
• Manufacturer: Renesas Electronics Corporation.

Chapter 4
134
Table 4-2
4.1.4 Start conditions
Note
After any reset release, the ring oscillator is always selected as the clock
source. The oscillation stabilization time for the ring oscillator is ensured by
hardware. The CPU clock VBCLK is derived from the ring oscillator.
Several clocks are operating based on the ring oscillator clock after reset. As
soon as the main oscillator, which is started by the internal firmware, is stable
the source of these clocks is automatically changed to the main oscillator.
Therefore depending on the firmware operation and the main oscillator
stabilization time these clocks may already be operating with the main
oscillator, when the user’s program is started.
Internal firmware starts the main oscillator. PLL and SSCG remain stopped.
When the firmware passes control to the application software, software has to
ensure that the main oscillator has stabilized and to start the PLL and SSCG.
Clock supply for most peripherals is not available unless the main oscillator
operates.
CPU access to peripherals that have no clock supply may cause system
deadlock.
Clock Generator status after reset release
a)
b)
Preliminary User’s Manual U17566EE1V2UM00
Item
Main oscillator
Sub oscillator
Ring oscillator
SSCG
PLL
VBCLK (CPU system)
IICLK
PCLK0, PCLK1
PCLK2…PCLK15
SPCLK0, SPCLK1
SPCLK2…SPCLK15
FOUTCLK
LCDCLK / WTCLK
WDTCLK
WCTCLK
Starts with ring oscillator, automatically changed to main oscillator, when main os-
cillator stable.
If the reset was caused by Power-On Clear (POC) or external RESET, the
clock source for LCDCLK and WTCLK is set to ring oscillator. If the reset
was caused by a different source, the clock selection for LCDCLK / WT-
CLK remains unchanged.
Status
stopped
operates
operates
stopped
stopped
operates
operates
operates
operates
operates
operates
operates
operates
operates
operates
b
Remarks
started by internal firmware
based on ring oscillator clock
based on ring/main oscillator clock
based on ring/main oscillator clock
based on ring/main oscillator clock
based on ring/main oscillator clock
based on ring/main oscillator clock
based on ring/main oscillator clock
based on ring/main oscillator clock
based on ring/main oscillator clock
based on ring/main oscillator clock
Clock Generator
a
a
a
a
a
a
a
a
a