13
SET RESOLUTION Command
The SET RESOLUTION
command is conditionally
enabled by the statement
“#define
ENABLE_RESOLUTION”. On
most systems this command is
not supported. If you wish to
disable this command in the
firmware, comment out the
aforementioned statement.
SET SCALING Command
The SET SCALING command is
conditionally enabled by the
statement “#define
ENABLE_SCALING”. On most
systems this command is not
supported. If you wish to
disable this command in the
firmware, comment out the
aforementioned statement.
Interrupt Service Routines (ISR)
The CY7C63743-PXC features
12 different sources of
interrupts. There are only four
ISRs implemented in this
application. If an interrupt is
enabled and the conditions for
the interrupts are met, the
microcontroller will generate
an interrupt. Upon servicing
the interrupt, the hardware
will first disable all interrupts
by clearing the Global
Interrupt Enable bit. This is
followed by an automatic
CALL instruction to the ROM
address of the interrupt being
serviced in the Interrupt
Vector. The instruction in the
Interrupt Vector is typically a
JMP instruction to the
Interrupt Service Routine
(ISR). A RETI or RET
instruction at the end of the
ISR brings the program
counter (PC) back to the
location prior to the interrupt
(POR and USB Bus Reset are
exceptions).
DualMain
– When power is
first applied to the
CY7C63743-PXC, a Power On
Reset (POR) occurs; the
microcontroller starts executing
code from address 0x00. This
is a JMP instruction to the
DualMain
routine. This routine
initializes the program stack
pointer (PSP), data stack
pointer (DSP), ram variables,
and the GPIO pins. This
routine calls
GetMouseType
which returns the interface of
the mouse. If a USB interface
is detected, the program jumps
to the
usbMain
loop.
Otherwise, the program goes to
the
ps2Main
loop.
DualUsbBusReset_ps2Error
–
The USB-PS2 Interrupt Mode
bit in the USB Status and
Control Register is defaulted to
“0”, or USB mode. This
indicates that the USB Bus
Reset interrupt will be
generated if the SE0 condition
(D+ and D- are both LOW)
exists for 256us. This ISR
enables the USB Device
Address, sets up the endpoint
modes and jumps to
usbMain
for the USB initialization.
Dual1msTimer
– This ISR
reads the current status of the
buttons. Therefore, every one
millisecond the button state is
updated; the button status
information will be used by
the
ProcessButtons
function at
a later time. This ISR
maintains the
dualInterface1ms
counter
variable which is used as a
1ms timing reference in other
parts of the program. This
routine also handles the
entrance/exit from suspend.
The mouse will prepare to
enter a suspend (low power)
state if there is no bus activity
in 3ms. If the mouse is
configured for remote wakeup,
the Bus Reset and wakeup
interrupts are enabled prior to
suspending the chip. The
program then enters a
suspended state, and will wake
at least as often as the
wakeup timer interrupts or as
a result of the USB Bus Reset
interrupt. Each time the chip
wakes up due to the wake up
timer interrupt, the state of
the buttons is examined by the
GetButtons
function. If a
change in the button state has
occurred, the mouse will
generate a resume signal to
the host and exit the ISR. If
the device is not enabled for
remote wakeup, only the USB
bus reset interrupt is enabled,
and the part is suspended.
Only a Bus Reset can wake up
the chip. If the resume was
due to bus activity, the
firmware returns to the main
loop. If the resume was due to
a button press, a K state is
driven upstream for 14
milliseconds prior to returning
to the main loop. Moving the
mouse will not wake the
suspended system.
DualUsbEndpoint0_ps2Error
–
This ISR is entered upon
receiving an Endpoint 0
interrupt. Endpoint 0
interrupts occur during the
Setup, data, and status phases
of a control transfer. This ISR
handler jumps to the proper
routine to handle one of these
phases.
DualUsbEndpoint1_ps2Error
–
This ISR is entered upon
receiving an Endpoint 1
interrupt. If the ACK bit is set,
indicating that a mouse packet
was just transmitted to the
host successfully, the SIE
automatically sets the endpoint
mode to NAK_IN mode, and
the data toggle bit is flipped
for the next transaction. The
data toggle bit should never be
toggled if the interrupt was a
result of a NAK transaction.
