CP3SP33SMSSLASHNOPB datasheet(185/407 Pages) TI1

185 / 407 page

Hidden

Receive

Buffer

CR16CAN

Buffer 0

BUFFER_ID

Buffer 13

BUFFER_ID

Buffer 14

BUFFER_ID

DS036

CP3SP33

www.ti.com

SNOSCW5 – MAY 2013

Figure 22-19. Receive Buffer

The following section gives an overview of the reception of the different types of frames.

The received data frame is stored in the first matching receive buffer beginning with buffer 0. For example,

if the message is accepted by buffer 5, then at the time the message will be copied, the RX request is

cleared and the CAN module will not try to match the frame to any subsequent buffer.

All contents of the hidden receive buffer are always copied into the respective receive buffer. This includes

the received message ID as well as the received Data Length Code (DLC); therefore when some mask

bits are set to don’t care, the ID field will get the received message ID which could be different from the

previous ID. The DLC of the receiving buffer will be updated by the DLC of the received frame. The DLC

of the received message is not compared with the DLC already present in the CNSTAT register of the

message buffer. This implies that the DLC code of the CNSTAT register indicates how may data bytes

actually belong to the latest received message.

The remote frames are handled by the CAN interface in two different ways. In the first method, remote

frames can be received like data frames by configuring the buffer to be RX_READY and setting the ID bits

including the RTR bit. In that case, the same procedure applies as described for Data Frames. In the

second method, a remote frame can trigger one or more message buffer to transmit a data frame upon

reception. This procedure is described under section Section 22.6.

22.5.1 Receive Timing

As soon as a CAN module receives a “dominant” bit on the CAN bus, the receive process is started. The

received ID and data will be stored in the hidden receive buffer if the global or basic acceptance filtering

matches. After the reception of the data, CAN module tries to match the buffer ID of buffer 0...14. The

data will be copied into the buffer after the reception of the 6th EOF bit as a message is valid at this time.

The copy process of every frame, regardless of the length, takes at least 17 CKI cycles (see also

Section 22.9.1). Figure 22-20 shows the receive timing.

Dual CAN Interfaces

185

Submit Documentation Feedback

Product Folder Links :CP3SP33

CP3SP33SMS/NOPB Datasheet(PDF) 185 Page - Texas Instruments

CP3SP33SMS/NOPB Datasheet(HTML) 185 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL