668-0011 Rabbit Semiconductor, 668-0011 Datasheet - Page 181

• Manufacturer Part Number: 668-0011
• Description: IC MPU RABIT3000A 55.5MHZ128LQFP
• Manufacturer: Rabbit Semiconductor

Specifications of 668-0011

• Rohs Status: RoHS non-compliant
• Processor Type: Rabbit 3000 8-Bit
• Speed: 55.5MHz
• Voltage: 2.5V, 2.7V, 3V, 3.3V
• Mounting Type: Surface Mount
• Package / Case: 128-LQFP
• Features: -
• Other names: 316-1043

20.2 Dependencies
20.2.1 I/O Pins
Each Input Capture channel can accept input from one of the following parallel port pins:
PC1, PC3, PC5, PC7, PD1, PD3, PD5, PD7, PF1, PF3, PF5, PF7, PG1, PG3, PG5, PG7.
Use ICTxR to select which input pin to trigger on.
Note that these pins can be used for other peripherals at the same time as the Input Capture
peripheral. For example, you can use Input Capture to use measure the pulse width on a
serial port input to measure the baud rate.
20.2.2 Clocks
The 16-bit Input Capture counters are clocked from the output of Timer A8, and can run at
rates from perclk/2 down to perclk/512 by writing the appropriate value to TAT8R.
20.2.3 Other Registers
Register
Function
TAT8R
Time constant for Input Capture clock.
20.2.4 Interrupts
Each Input Capture channel can generate an interrupt whenever a start/stop condition
occurs, or when the counter rolls over to zero. The interrupt request is cleared when
ICCSR is read.
The Input Capture interrupt vector is in the IIR at offset 0x1A0. It can be set as Priority 1,
2, or 3.
The Input Capture channels synchronize their inputs to the peripheral clock (further
divided by Timer A8). Since the inputs are only sampled in synch with the peripheral
clock, any faster state faster changes cannot be detected, which is akin to a digital low-
pass filter functionality on the inputs. Because of this, there is some delay between the
input transition and when an interrupt is requested, as shown below. The status bits in
ICSxR are set coincident with the interrupt request and are reset when read from the
ICSxR.
Chapter 20 Input Capture
171