STR720 datasheet(255/401 Pages) STMICROELECTRONICS

Part #	STR720

Description	ARM720T 16/32-BIT MCU WITH 16K RAM, USB, CAN, 3 TIMERS, ADC, 6 COMMUNICATIONS INTERFACES

PDF	401 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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255 / 401 page

STR720 - CONTROLLER AREA NETWORK (CAN)

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The examples in Figure 38 show how short dominant noise spikes are filtered by

synchronizations. In both examples the spike starts at the end of Prop_Seg and has the

length of “Prop_Seg + Phase_Seg1”.

In the first example, the Synchronization Jump Width is greater than or equal to the phase

error of the spike’s edge from recessive to dominant. Therefore the Sample Point is shifted

after the end of the spike; a recessive bus level is sampled.

In the second example, SJW is shorter than the phase error, so the Sample Point cannot be

shifted far enough; the dominant spike is sampled as actual bus level.

Figure 38. Filtering of Short Dominant Spikes

recessive

dominant

Sync_Seg

Prop_Seg

Phase_Seg1

Phase_Seg2

Spike

Rx-Input

Sample-Point

recessive

dominant

Spike

Rx-Input

SJW

≥ Phase Error

SJW < Phase Error

STR720 Datasheet(PDF) 255 Page - STMicroelectronics