AN2131QC Cypress Semiconductor Corp, AN2131QC Datasheet - Page 191

• Manufacturer Part Number: AN2131QC
• Description: IC MCU 8051 8K RAM 24MHZ 80BQFP
• Manufacturer: Cypress Semiconductor Corp
• Series: EZ-USB®r

Specifications of AN2131QC

• Applications: USB Microcontroller
• Core Processor: 8051
• Program Memory Type: ROMless
• Controller Series: AN213x
• Ram Size: 8K x 8
• Interface: I²C, USB
• Number Of I /o: 24
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 80-QFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 428-1307

The EZ-USB oscillator re-starts when:
After an oscillator stabilization time, the EZ-USB core asserts the 8051 Resume interrupt
(Figure 9-1). This causes the 8051 to exit its idle mode. The Resume interrupt is the high-
est priority 8051 interrupt. It is always enabled, unaffected by the EA bit.
The resume ISR clears the interrupt request flag, and executes an “reti” (return from inter-
rupt) instruction. This causes the 8051 to continue program execution at the instruction
following the one that set PCON.0 to initiate the suspend operation.
Two bits in the USBCS register are used for remote wakeup, WAKESRC and SIGR-
SUME.
After exiting the idle state, the 8051 reads the WAKESRC bit in the USBCS register to
discover how the wakeup was initiated. WAKESRC=1 indicates assertion of the
WAKEUP# pin, and WAKESRC=0 indicates a resumption of USB bus activity. The 8051
clears the WAKESRC bit by writing a “1” to it.
Page 11-4
USBCS
About the ‘Resume’ Interrupt
The 8051 enters the idle mode when PCON.0 is set to “1.” Although the 8051 exits its
idle state when any interrupt occurs, the EZ-USB logic supports only the RESUME inter-
rupt for the USB resume operation. This is because the EZ-USB core asserts this partic-
ular interrupt after restarting the 8051 clock.
11.4
WAKESRC
•
•
b7
USB bus activity resumes (shown as “USB Resume” in Figure 11-3), or
External logic asserts the EZ-USB WAKEUP# pin low.
Remote Wakeup
b6
-
Figure 11-4. USB Control and Status Register
b5
-
Chapter 11. EZ-USB Power Management
USB Control and Status
b4
-
DISCON
b3
DISCOE
b2
RENUM
b1
EZ-USB TRM v1.9
SIGRSUME
b0
7FD6