CY7C65113C
Document #: 38-08002 Rev. *D Page 23 of 49
13.0 Processor Status and Control Register Bit 0: Run
This bit is manipulated by the HALT instruction. When Halt is executed, all the bits of the Processor Status and Control
Register are cleared to 0. Since the run bit is cleared, the processor stops at the end of the current instruction. The processor
remains halted until an appropriate reset occurs (power-on or Watchdog). This bit should normally be written as a ‘1.’
Bit 1: Reserved
Bit 1 is reserved and must be written as a zero.
Bit 2: Interrupt Enable Sense
This bit indicates whether interrupts are enabled or disabled. Firmware has no direct control over this bit as writing a zero
or one to this bit position has no effect on interrupts. A ‘0’ indicates that interrupts are masked off and a ‘1’ indicates that
the interrupts are enabled. This bit is further gated with the bit settings of the Global Interrupt Enable Register (Figure 14-1)
and USB End Point Interrupt Enable Register (Figure 14-2). Instructions DI, EI, and RETI manipulate the state of this bit.
Bit 3: Suspend
Writing a ‘1’ to the Suspend bit halts the processor and cause the microcontroller to enter the suspend mode that signifi-
cantly reduces power consumption. A pending, enabled interrupt or USB bus activity causes the device to come out of
suspend. After coming out of suspend, the device resumes firmware execution at the instruction following the IOWR which
put the part into suspend. An IOWR attempting to put the part into suspend is ignored if USB bus activity is present. See
Section 8.0 for more details on suspend mode operation.
Bit 4: Power-on Reset
The Power-on Reset is set to ‘1’ during a power-on reset. The firmware can check bits 4 and 6 in the reset handler to
determine whether a reset was caused by a power-on condition or a Watchdog timeout. A POR event may be followed by
a Watchdog reset before firmware begins executing, as explained below.
Bit 5: USB Bus Reset Interrupt
The USB Bus Reset Interrupt bit is set when the USB Bus Reset is detected on receiving a USB Bus Reset signal on the
upstream port. The USB Bus Reset signal is a single-ended zero (SE0) that lasts from 12 to 16 µs. An SE0 is defined as
the condition in which both the D+ line and the D– line are LOW at the same time.
Bit 6: Watchdog Reset
The Watchdog Reset is set during a reset initiated by the Watchdog Timer. This indicates the Watchdog Timer went for
more than tWATCH (8 ms minimum) between Watchdog clears. This can occur with a POR event, as noted below.
Bit 7: IRQ Pending
The IRQ pending, when set, indicates that one or more of the interrupts has been recognized as active. An interrupt remains
pending until its interrupt enable bit is set (Figure 14-1, Figure 14-2) and interrupts are globally enabled. At that point, the
internal interrupt handling sequence clears this bit until another interrupt is detected as pending.
During power-up, the Processor Status and Control Register is set to 00010001, which indicates a POR (bit 4 set) has occurred
and no interrupts are pending (bit 7 clear). During the 96-ms suspend at start-up (explained in Section 7.1), a Watchdog Reset
also occurs unless this suspend is aborted by an upstream SE0 before 8 ms. If a WDR occurs during the power-up suspend
interval, firmware reads 01010001 from the Status and Control Register after power-up. Normally, the POR bit should be cleared
so a subsequent WDR can be clearly identified. If an upstream bus reset is received before firmware examines this register, the
Bus Reset bit may also be set.
During a Watchdog Reset, the Processor Status and Control Register is set to 01XX0001, which indicates a Watchdog Reset (bit
6 set) has occurred and no interrupts are pending (bit 7 clear). The Watchdog Reset does not effect the state of the POR and the
Bus Reset Interrupt bits.
Processor Status and Control Address 0xFF
Bit # 76543210
Bit Name IRQ
Pending
Watchdog
Reset
USB Bus
Reset
Interrupt
Power-on
Reset
Suspend Interrupt
Enable
Sense
Reserved Run
Read/Write R R/W R/W R/W R/W R R/W R/W
Reset 00010001
Figure 13-1. Processor Status and Control Register
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