LPC1112FHN33/203,5 NXP Semiconductors, LPC1112FHN33/203,5 Datasheet - Page 303

• Manufacturer Part Number: LPC1112FHN33/203,5
• Description: ARM Microcontrollers - MCU Cortex-M0 16kB flash up to 4 kB SRAM
• Manufacturer: NXP Semiconductors

Specifications of LPC1112FHN33/203,5

• Rohs: yes
• Core: ARM Cortex M0
• Processor Series: LPC1112
• Data Bus Width: 32 bit
• Maximum Clock Frequency: 50 MHz
• Program Memory Size: 16 KB
• Data Ram Size: 4 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
16.7.3.2 Data Transfer between IFx Registers and the Message RAM
16.7.3.3 Transmission of messages between the shift registers in the CAN core and
When the INIT bit in the CAN Control Register is cleared, the CAN Protocol Controller
state machine of the CAN core and the Message Handler State Machine control the CAN
controller’s internal data flow. Received messages that pass the acceptance filtering are
stored into the Message RAM, and messages with pending transmission request are
loaded into the CAN core’s shift register and are transmitted via the CAN bus.
The CPU reads received messages and updates messages to be transmitted via the IFx
Interface Registers. Depending on the configuration, the CPU is interrupted on certain
CAN message and CAN error events.
When the CPU initiates a data transfer between the IFx Registers and Message RAM, the
Message Handler sets the BUSY bit in the respective Command Register to ‘1’. After the
transfer has completed, the BUSY bit is set back to ‘0’.
The Command Mask Register specifies whether a complete Message Object or only parts
of it will be transferred. Due to the structure of the Message RAM it is not possible to write
single bits/bytes of one Message Object. Software must always write a complete Message
Object into the Message RAM. Therefore the data transfer from the IFx Registers to the
Message RAM requires a read-modify-write cycle:
the Message buffer
If the shift register of the CAN Core cell is ready for loading and if there is no data transfer
between the IFx Registers and Message RAM, the MSGVAL bits in the Message Valid
Register TXRQST bits in the Transmission Request Register are evaluated. The valid
Message Object with the highest priority pending transmission request is loaded into the
shift register by the Message Handler and the transmission is started. The Message
Object’s NEWDAT bit is reset.
After a successful transmission and if no new data was written to the Message Object
(NEWDAT = ‘0’) since the start of the transmission, the TXRQST bit will be reset. If TXIE
is set, INTPND will be set after a successful transmission. If the CAN controller has lost
the arbitration or if an error occurred during the transmission, the message will be
retransmitted as soon as the CAN bus is free again. If meanwhile the transmission of a
message with higher priority has been requested, the messages will be transmitted in the
order of their priority.
1. Read the parts of the message object that are not to be changed from the message
2. Write the complete contents of the message buffer registers into the message object.
RAM using the command mask register.
– After the partial read of a Message Object, the Message Buffer Registers that are
– After the partial write of a Message Object, the Message Buffer Registers that are
not selected in the Command Mask Register will be left unchanged.
not selected in the Command Mask Register will set to the actual contents of the
selected Message Object.
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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