LPC1114FHN33/203,5 NXP Semiconductors, LPC1114FHN33/203,5 Datasheet - Page 304

• Manufacturer Part Number: LPC1114FHN33/203,5
• Description: ARM Microcontrollers - MCU Cortex-M0 32 kB Fl 8 kB SRAM
• Manufacturer: NXP Semiconductors

Specifications of LPC1114FHN33/203,5

• Rohs: yes
• Core: ARM Cortex M0
• Processor Series: LPC1114
• Data Bus Width: 32 bit
• Maximum Clock Frequency: 50 MHz
• Program Memory Size: 32 KB
• Data Ram Size: 8 KB
• On-chip Adc: Yes
• Operating Supply Voltage: 1.8 V to 3.6 V
• Operating Temperature Range: - 65 C to + 150 C
• Package / Case: HVQFN-33
• Mounting Style: SMD/SMT
• Factory Pack Quantity: 260

NXP Semiconductors
UM10398
User manual
16.7.3.4.1 Reception of a data frame
16.7.3.4.2 Reception of a remote frame
16.7.3.4 Acceptance filtering of received messages
When the arbitration and control field (Identifier + IDE + RTR + DLC) of an incoming
message is completely shifted into the Rx/Tx Shift Register of the CAN Core, the
Message Handler state machine starts the scanning of the Message RAM for a matching
valid Message Object.
To scan the Message RAM for a matching Message Object, the Acceptance Filtering unit
is loaded with the arbitration bits from the CAN Core shift register. Then the arbitration and
mask fields (including MSGVAL, UMASK, NEWDAT, and EOB) of Message Object 1 are
loaded into the Acceptance Filtering unit and compared with the arbitration field from the
shift register. This is repeated with each following Message Object until a matching
Message Object is found or until the end of the Message RAM is reached.
If a match occurs, the scanning is stopped and the Message Handler state machine
proceeds depending on the type of frame (Data Frame or Remote Frame) received.
The Message Handler state machine stores the message from the CAN Core shift register
into the respective Message Object in the Message RAM. The data bytes, all arbitration
bits, and the Data Length Code are stored into the corresponding Message Object. This is
implemented to keep the data bytes connected with the identifier even if arbitration mask
registers are used.
The NEWDAT bit is set to indicate that new data (not yet seen by the CPU) has been
received. The CPU/software should reset NEWDAT when it reads the Message Object. If
at the time of the reception the NEWDAT bit was already set, MSGLST is set to indicate
that the previous data (supposedly not seen by the CPU) is lost. If the RxIE bit is set, the
INTPND bit is also set, causing the Interrupt Register to point to this Message Object.
The TXRQST bit of this Message Object is reset to prevent the transmission of a Remote
Frame, while the requested Data Frame has just been received.
When a Remote Frame is received, three different configurations of the matching
Message Object have to be considered:
1. DIR = ‘1’ (direction = transmit), RMTEN = ‘1’, UMASK = ‘1’ or’0’
2. DIR = ‘1’ (direction = transmit), RMTEN = ‘0’, UMASK = ’0’
3. DIR = ‘1’ (direction = transmit), RMTEN = ‘0’, UMASK = ’1’
On the reception of a matching Remote Frame, the TXRQST bit of this Message
Object is set. The rest of the Message Object remains unchanged.
On the reception of a matching Remote Frame, the TXRQST bit of this Message
Object remains unchanged; the Remote Frame is ignored.
On the reception of a matching Remote Frame, the TXRQST bit of this Message
Object is reset. The arbitration and control field (Identifier + IDE + RTR + DLC) from
the shift register is stored into the Message Object in the Message RAM, and the
NEWDAT bit of this Message Object is set. The data field of the Message Object
remains unchanged; the Remote Frame is treated similar to a received Data Frame.
All information provided in this document is subject to legal disclaimers.
Rev. 12 — 24 September 2012
Chapter 16: LPC111x/LPC11Cxx C_CAN controller
UM10398
© NXP B.V. 2012. All rights reserved.
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