20-668-0024 Rabbit Semiconductor, 20-668-0024 Datasheet - Page 233

• 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

21.3 Operation
21.3.1 Input-Capture Channel
The following steps explain how to set up an input-capture channel.
1. Configure Timer A8 via TAT8R to provide the desired input-capture clock.
2. Configure ICTxR to provide the desired start/stop operation and conditions.
3. Configure ICSxR to select the input pins for the start and stop conditions.
4. Configure ICCR to select either the count or the capture mode.
5. Reset the counter by writing to ICCSR.
21.3.2 Handling Interrupts
The following steps explain how an interrupt is used.
1. Write the vector to the interrupt service routine to the internal interrupt table
2. Configure the Input Capture Control/Status Register (ICCSR) to select events that will
3. Configure the Input Capture Control Register (ICCR) to select the interrupt priority
The following actions occur within the interrupt service routine.
• If needed, the current counter value can be read from ICLxR and LCMxR (reading
• If the counter is expected to roll over, determine if that is why the interrupt occurred by
• The interrupt request should be cleared by reading from ICCSR
21.3.3 Example ISR
A sample interrupt handler is shown below.
Chapter 21 Input Capture
generate an interrupt.
(note that interrupts will be enabled once this value is set; this step should be done last).
from ICLxR latches the value of ICLxR, so ICLxR should always be read first)
reading the status bits in ICCSR and adjusting any software counters accordingly
ic_isr::
push af
ioi ld a, (ICCSR)
; determine which interrupts have occurred
; if rollover, perform any necessary software counter adjustments here
; read counter values
pop af
ipres
ret
; clear the interrupt request and get status
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