Microcontrollers User manual

UM10237_2 © NXP B.V. 2008. All rights reserved.
User manual Rev. 02 — 19 December 2008 514 of 792
NXP Semiconductors
UM10237
Chapter 18: LPC24XX CAN controllers CAN1/2
17.3.2 Scenario 2: Message lost
In this scenario a first FullCAN Message is stored and read out by Software (1
st
Object
write and read). In a second course a second message is stored (2
nd
Object write) but not
read out before a third message gets stored (3
rd
Object write). Since the FullCAN Interrupt
of that Object (IntPndx) is already asserted, the Message Lost Signal gets asserted.
Fig 85. Normal case, no messages lost
01 11
IntPndx
semaphore
bits
look-up
table
access
00
MsgLostx
message
handler
access
ARM
processor
access
read
SEM
read
D2
read
D1
clear
SEM
read
SEM
write
SEM
write
D2
write
D1
Write
ID, SEM
Fig 86. Message lost
01 11 01 11 1100
1st Object
write
2nd Object
write
1st Object
read
3rd Object
write
IntPndx
semaphore
bits
look-up
table
access
MsgLostx
message
handler
access
ARM
processor
access
read
SEM
read
D2
read
D1
clear
SEM
read
SEM
write
SEM
write
D2
write
D1
write
ID,
SEM
write
SEM
write
D2
write
D1
write
ID,
SEM
write
SEM
write
D2
write
D1
write
ID,
SEM