NUC130VE3CN Nuvoton Technology Corporation of America, NUC130VE3CN Datasheet - Page 382

• Manufacturer Part Number: NUC130VE3CN
• Description: IC MCU 32BIT 128KB FLASH 100LQFP
• Manufacturer: Nuvoton Technology Corporation of America
• Series: NuMicro™ NUC100r

Specifications of NUC130VE3CN

• Core Processor: ARM Cortex-M0
• Core Size: 32-Bit
• Speed: 50MHz
• Connectivity: CAN, EBI/EMI, I²C, IrDA, LIN, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, DMA, I²S, POR, PWM, WDT
• Number Of I /o: 80
• Program Memory Size: 128KB (128K x 8)
• Program Memory Type: FLASH
• Eeprom Size: -
• Ram Size: 16K x 8
• Voltage - Supply (vcc/vdd): 2.5 V ~ 5.5 V
• Data Converters: A/D 8x12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 100-LQFP
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

5.13.6.9 Handling Interrupts
5.13.6.10 Configuring the Bit Timing
5.13.6.10.1 Bit Time and Bit Rate
If several interrupts are pending, the CAN Interrupt Register will point to the pending interrupt with
the highest priority, disregarding their chronological order. An interrupt remains pending until the
application software has cleared it.
The Status Interrupt has the highest priority. Among the message interrupts, interrupt priority of
the Message Object decreases with increasing message number.
A message interrupt is cleared by clearing the IntPnd bit of the Message Object. The Status
Interrupt is cleared by reading the Status Register.
The interrupt identifier, IntId , in the Interrupt Register, indicates the cause of the interrupt. When
no interrupt is pending, the register will hold the value zero. If the value of the Interrupt Register is
different from zero, then there is an interrupt pending and, if IE is set, the CAN_INT interrupt
signal is active. The interrupt remains active until the Interrupt Register is back to value zero (the
cause of the interrupt is reset) or until IE is reset.
The value 0x8000 indicates that an interrupt is pending because the CAN Core has updated (not
necessarily changed) the Status Register (Error Interrupt or Status Interrupt). This interrupt has
the highest priority. The application software can update (reset) the status bits RxOk , TxOk and
LEC, but a write access of the software to the Status Register can never generate or reset an
interrupt.
All other values indicate that the source of the interrupt is one of the Message Objects. IntId
points to the pending message interrupt with the highest interrupt priority.
The application software controls whether a change of the Status Register may cause an interrupt
(bits EIE and SIE in the CAN Control Register) and whether the interrupt line becomes active
when the Interrupt Register is different from zero (bit IE in the CAN Control Register). The
Interrupt Register will be updated even when IE is reset.
The application software has two possibilities to follow the source of a message interrupt. First, it
can follow the IntId in the Interrupt Register and second it can poll the Interrupt Pending Register.
An interrupt service routine that is reading the message that is the source of the interrupt may
read the message and reset the Message Object’s IntPnd at the same time (bit ClrIntPnd in the
Command Mask Register). When IntPnd is cleared, the Interrupt Register will point to the next
Message Object with a pending interrupt.
Even if minor errors in the configuration of the CAN bit timing do not result in immediate failure,
the performance of a CAN network can be reduced significantly.
In many cases, the CAN bit synchronization will amend a faulty configuration of the CAN bit timing
to such a degree that only occasionally an error frame is generated. However, in the case of
arbitration, when two or more CAN nodes simultaneously try to transmit a frame, a misplaced
sample point may cause one of the transmitters to become error passive.
The analysis of such sporadic errors requires a detailed knowledge of the CAN bit
synchronization inside a CAN node and interaction of the CAN nodes on the CAN bus.
CAN supports bit rates in the range of lower than 1 kBit/s up to 1000 kBit/s. Each member of the
CAN network has its own clock generator, usually a quartz oscillator. The timing parameter of the
NuMicro™ NUC130/NUC140 Technical Reference Manual
- 382 -
Publication Release Date: June 14, 2011
Revision V2.01