English
Language : 

LM3S2939 Datasheet, PDF (559/749 Pages) Texas Instruments – Stellaris® LM3S2939 Microcontroller
Stellaris® LM3S2939 Microcontroller
15.3.11.3 Reading from a FIFO Buffer
When the CPU transfers the contents of a message object from a FIFO buffer by writing its number
to the CANIFnCRQ, the TXRQST and CLRINTPND bits in the CANIFnCMSK register should be set
such that the NEWDAT and INTPEND bits in the CANIFnMCTL register are cleared after the read.
The values of these bits in the CANIFnMCTL register always reflect the status of the message
object before the bits are cleared. To assure the correct function of a FIFO buffer, the CPU should
read out the message objects starting with the message object with the lowest message number.
When reading from the FIFO buffer, the user should be aware that a new received message is
placed in the message object with the lowest message number for which the NEWDAT bit of the
CANIFnMCTL register. As a result, the order of the received messages in the FIFO is not guaranteed.
Figure 15-3 on page 560 shows how a set of message objects which are concatenated to a FIFO
Buffer can be handled by the CPU.
June 18, 2012
559
Texas Instruments-Production Data