UM0434 datasheet(352/390 Pages) STMICROELECTRONICS

352 / 390 page

UM0434

Nexus3 module

353/391

Note:

When DC1[PTM] is set, direct branch messages are not transmitted. Instead, each direct

branch or predicated instruction toggles a bit in the history buffer.

Resource full messages

The resource full message is used in conjunction with the branch history messages. The

resource full message is generated when the internal branch/predicate history buffer is full.

If synchronization is needed at the time this message is generated, the synchronization is

delayed until the next branch trace message that is not a resource full message.

For history buffer overflow, the resource full message transmits a resource code (RCODE)

of 0b0001 and the current contents of the history buffer, including the stop bit, are

transmitted in the resource data (RDATA) field. This history information can be concatenated

by the development tool with the branch/predicate history information from subsequent

messages to obtain the complete branch/predicate history between indirect changes of flow.

For instruction counter overflow, the resource full message transmits an RCODE of 0b0000

and a value of 0xFF is transmitted in the RDATA field, indicating that 255 sequential

instructions have been executed since the last change of flow or, if program trace is in

history mode, since the last instruction that recorded history information

Table 250 shows the RCODE encodings and RDATA information used for Resource Full

messages.

Debug status messages

Debug status messages report low-power mode and debug status. Debug status messages

are enabled when Nexus 3 is enabled. Entering/exiting debug mode as well as entering a

low-power mode triggers a debug status message, indicating the value of the most

significant byte in the development status register. Debug status information is sent out in

the format shown in

Table 251:

Table 249.

Direct Branch Message Format

(1–8 bits)

(4 bits)

(6 bits)

Sequence Count

Source Process

TCODE (000011)

Maximum Length = 18 bits; minimum length = 11 bits

Figure 73.

Resource full message format

(1–32 bits)

(4 bits)

(6 bits)

Branch History

RCODE

(0001)

Source

Process

TCODE

(011011)

Maximum length = 46 bits; minimum length = 15 bits

Table 250.

RCODE encoding

RCODE

RDATA field

Description

0000

0xFF

Program trace instruction counter reached 255

and was reset.

0001

Branch history. This type of packet is

terminated by a stop bit set after the

last history bit.

Program trace, branch/predicate instruction

history full.

UM0434 Datasheet(PDF) 352 Page - STMicroelectronics

UM0434 Datasheet(HTML) 352 Page - STMicroelectronics

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