20-668-0024 Rabbit Semiconductor, 20-668-0024 Datasheet - Page 245

• Manufacturer Part Number: 20-668-0024
• Description: IC CPU RABBIT4000 128-LQFP
• Manufacturer: Rabbit Semiconductor

Specifications of 20-668-0024

• Processor Type: Rabbit 4000 8-bit
• Speed: 60MHz
• Voltage: 2.5V, 2.7V, 3V, 3.3V
• Mounting Type: Surface Mount
• Package / Case: 128-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Other names: 20-668-0022; 316-1078

22.3 Operation
The following steps explain how to set up a Quadrature Decoder channel.
1. Configure Timer A10 via TAT10R to provide the desired Quadrature Decoder clock
2. Configure QDCR to select the input pins for the two channels.
3. Reset the counters by writing to QDCSR.
22.3.1 Handling Interrupts
The following steps explain how an interrupt is set up and used.
1. Write the vector to the interrupt service routine to the internal interrupt table.
2. Configure QDCR to select the interrupt priority (note that interrupts will be enabled
The following actions occur within the interrupt service routine.
• Since a Quadrature Decoder interrupt occurs when the counter rolls over, determine
• The current counter value can be read from QDCxR (and QDCxHR if the 10-bit
22.3.2 Example ISR
A sample interrupt handler is shown below.
Chapter 22 Quadrature Decoder
speed.
once this value is set).
exactly why the interrupt occurred by reading the status bits in QDCSR and adjust any
software counters accordingly. This will also clear the interrupt request.
counter is enabled).
qd_isr::
push af
ioi ld a, (QDCSR)
; perform any necessary software counter adjustments here
; read current counter value(s)
pop af
ipres
ret
; save used registers
; clear the interrupt request and get status
; restore used registers
235