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WDT Reset
WDE
PURS
USBCTL Register
MCNFG Register
USB Function Reset
FRSTE
RESET
MCU
All Internal MMR
RST
USBR
2.8 Pullup Resistor Connect/Disconnect
D+
TUSB3210
DM0
DP0
CMOS
CONT-BitPUR
1.5 kΩ
15 kΩ15 kΩ
HUB
D-
TUSB2036A
2.9 8052 Interrupt and Status Registers
TUSB3210
Universal Serial Bus
General-Purpose Device Controller
SLLS466F – FEBRUARY 2001 – REVISED AUGUST 2007
Figure 2-2. Reset Diagram
After reading firmware into RAM, the TUSB3210 can re-enumerate using the new firmware (no need to
physically disconnect and re-connect the cable). Figure 2-3 shows an equivalent circuit implementation for
Connect and Disconnect from a USB upstream port (also see Figure 4-3 b). When the CONT bit in the
USBCTL register is 1, the CMOS driver sources V
DD
to the pullup resistor (PUR pin) presenting a normal
connect condition to the USB hub (high speed). When the CONT bit is 0, the PUR pin is driven low. In this
state, the 1.5-k Ω resistor is connected to GND, resulting in device disconnection state. The PUR driver is
a CMOS driver that can provide V
DD
– 0.1 V minimum at 8 mA of source current.
Figure 2-3. Pullup Resistor Connect/Disconnect Circuit
All seven 8052-standard interrupt sources are preserved. SIE is the standard interrupt enable register,
which controls the seven interrupt sources. All the additional interrupt sources are connected together as
an OR to generate INT0. The INT0 signal is provided to interrupt the MCU (see interrupt connection
diagram, Figure 2-4 ).
Table 2-7. 8052 Interrupt Location Map
INTERRUPT DESCRIPTION START COMMENTS
SOURCE ADDRESS
ET2 Timer-2 interrupt 002Bh
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