US 7,804,854 B2Granted

Digital message transmission protocol

AssigneeSTMicroelectronics S.r.l.

InventorLaurent Regnier

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Abstract

A method for transmitting digital messages used during testing of microprocessors. Each message includes at least one data packet. To transmit a message, each data packet is divided into successive segments of predetermined size, each segment being classified in accordance with one or the other among five types depending on whether it contains a start of message (SM), intermediate data (NT), an end of packet (EP), and end of message (EM); or it is an empty segment (ID). As each segment is sent, an identification signal characterizing the succession of the segment concerned and of the preceding segment is sent. To reduce the number of transmitted segments, a segment containing both the start and the end of a message is classified as being a segment containing an end of message, and a segment containing both the start of a message and the end of a first packet of the message being classified as a segment containing an end of packet.

Claims19

Dependent claims

A method for transmitting, between a monitoring circuit integrated with a microprocessor and an analysis tool, digital messages, each message comprising at least one data packet, the method comprising:

a/ for each message of the digital messages, dividing each data packet of a digital message into at least one successive segments of a same predetermined size, each segment of the successive segments being classified according to at least one of the five following types of segments:
a first type of segment, each segment classified as the first type containing a message start;
a second type of segment, each segment classified as the second type containing intermediary data;
a third type of segment, each segment classified as the third type containing a packet end;
a fourth type of segment, each segment classified as the fourth type containing a message end;
or
a fifth type of segment, each segment classified as the fifth type being an empty segment;
b/ sending, by the monitoring circuit, at a same time as each segment of the successive segments, an identification signal characterizing a type difference between a considered segment and a previous segment;
and
c/ reconstituting, by the analysis tool, the packets of the digital message by arranging end to end the successive segments containing data of a same packet;
wherein a segment of the successive segments having both the start and the end of the digital message is classified as the fourth type of segment, and
wherein, if the message that includes at least one data packet comprises a plurality of data packets and if a segment of the successive segments has both the start of the digital message and the end of a first packet among the plurality of packets of the digital message, the segment is classified as the third type of segment.

9 more elements

A system for transmitting, between a monitoring circuit integrated to a microprocessor and an analysis tool, digital messages, each digital message comprises at least one data packet, the device comprising:

means for dividing each data packet of a digital message into at least one successive segments of same predetermined size, each segment of the successive segments being classified according to at least one of the five following segment types:
segment containing a message start;
segment containing intermediary data;
segment containing a packet end;
segment containing a message end;
or
empty segment;
means for sending at the same time as each segment of the successive segments, an identification signal characterizing the type difference between a considered segment and a previous segment;
and
means for reconstituting the packets of the digital message by arranging end to end the successive segments containing data of a same packet;
wherein the means for dividing each data packet classifies a segment of the successive segments having both the start and the end of the digital message is classified as a message end segment, and
wherein, if the message that includes at least one data packet comprises a plurality of data packets and if a segment of the successive segments has both the start of the digital message and the end of a first packet among the plurality of packets of the digital message, the segment is classified as being a packet end segment.

9 more elements

Dependencies are inferred from the claim text.