Renesas M16C Series User Manual

Frequency Synthesizer
M30240 Group
Rev.1.00 Sep 24, 2003 Page 132 of 360
1.5.1.2 Set up of Frequency Synthesizer and DC-DC Converter
Figure 1.117: PLL, DC-DC Converter and USB Functional Block Diagram
A functional block diagram of the USB system on the M30240 which shows how the control signals
affect operation is given in Figure 1.117
1.5.1.3 Set up after Hardware Reset
A Hardware Reset occurs when either the RESET
pin is brought low for more than 2 µs or an invalid
opcode is fetched by the CPU. The frequency synthesizer (PLL) and DC-DC converter should be set
up as follows in the Hardware Reset routine (see Figure 1.118),
• Power up the M30240 and other components on the peripheral device for less than 100 mA opera-
tion. The current limit only applies for bus powered devices.
• Configure the PLL for 48MHz f(VCO) operation.
• Enable the PLL by setting FSE (bit 0 of the Frequency Synthesizer Control Register (FSC)) to a “1”,
then wait for 2 ms.
• Check the lock status bit (LS, bit 7 of FSC).
• If the bit is a “1”, go on.
• If the bit is a “0”, wait 0.1 ms longer and then re-check the bit.
• Enable the DC-DC converter in high current mode by setting USBC4 (bit 4 of the USB Control Reg-
ister (USBC)) to a “1” and keeping USBC3 (bit 3 of USBC) a “0”. High current mode should always
be used during normal USB operation. Low current mode should only be used during a USB sus-
pend.
• Wait (C + 1)ms (where C equals the external capacitance connected to the Ext Cap pin in µF) for
the voltage on Ext Cap to reach a steady state voltage of approximately 3.3V. (Since the D+ pullup
is connected to the Ext Cap pin, the upstream hub will detect that the peripheral device has been
plugged in once the voltage on D+ reaches approximately 2.0 V.)
•Example: A 2.2 µF capacitor connected to Ext Cap requires 3.2 ms for the voltage on Ext Cap to be stable.
• Enable the USB clock by setting USBC5 (bit 5 of USBC) to a “1”. (If the USB clock and FCU are
enabled before the voltage on Ext Cap is stable, a phantom USB Reset may be detected, or the ac-
tual USB Reset may not be detected.)
• Wait at least 4 cycles of Φ, then enable the USB FCU by setting USBC7 (bit 7 of USBC) to a “1”.
• Enable other blocks as necessary.
27-33 Ω
27-33 Ω
D+
D-
USB FCU
2.2 µ F
0.1 µ F
Ext Cap
Frequency
Synthesizer
f(Xin)
FSE LS
1.5 k
Ω
USB Transceiver
DC-DC Converter
USBC3
USBC4
USBC7
USBC7
USBC5
USBCLK
(48MHz)
enable lock
enable
enable
(enable)
(enable)
enable
current
mode

Renesas M16C Series Specifications

General

Brand	Renesas
Model	M16C Series
Category	Computer Hardware
Language	English