CP3SP33SMSSLASHNOPB datasheet(187/407 Pages) TI1

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Yes

Ye s

Read buffer

Exit

Interrupt Entry Point

Read CNSTAT

Write RX_READY

Read CNSTAT

Clear RX_PND

Read buffer (id/data/control)

RX_READY?

RX_BUSYx?

RX_FULL or

RX_OVERRUN?

(optional, for information)

Yes

DS038

CP3SP33

www.ti.com

SNOSCW5 – MAY 2013

Figure 22-21. Buffer Read Routine (BUFFLOCK Disabled)

The first step is only applicable if polling is used to get the status of the receive buffer. It can be deleted

for an interrupt driven receive routine.

1. Read the status (CNSTAT) of the receive buffer. If the status is RX_READY, no was the message

received, so exit. If the status is RX_BUSY, the copy process from hidden receive buffer is not

completed yet, so read CNSTAT again.

If a buffer is configured to RX_READY and its interrupt is enabled, it will assert an interrupt as soon as

the buffer has received a message and entered the RX_FULLstate (see also Section 22.7). In that

case the procedure described below must be followed.

2. Read the status to determine if a new message has overwritten the one originally received which

triggered the interrupt.

3. Write RX_READY into CNSTAT.

4. Read the ID/data and object control (DLC/RTR) from the message buffer.

Dual CAN Interfaces

187

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CP3SP33SMS/NOPB Datasheet(PDF) 187 Page - Texas Instruments