Microcontroller information extraction system and method

Abstract

A system for debugging a device under test may include a processor register with a program count and a debug program register that receives the program count upon execution of an instruction by a processor. In one implementation, a microcontroller under test by a debugger is accessed using a serial interface, such as a JTAG interface. The interface can communicate directly with a debug register to retrieve program count values, both when the microcontroller is halted and when it is executing instructions. The polling interval to retrieve the program count values may be adjusted by a user of the debugger based on considerations such as bandwidth and accuracy. The microcontroller may transmit the program count value to the debug register from a processing register that is not accessible to the debugger.

1 - 21 . (canceled) 
   
   
       22 . A system comprising:
 a processing unit on an integrated device, the processing unit including a processing program counter where the processing unit stores addresses for instructions executed by the processing unit;   a program counter on the integrated device, wherein every time the processing unit executes any of the instructions, the processing unit also automatically transmits a value from the processing program counter to the program counter; and   a serial interface to dynamically transfer the value from the program counter to an external device while the processing unit is executing the instructions.   
   
   
       23 . The system of  claim 22 , wherein the processing unit halts execution, based on a halt instruction transmitted from the external device, before retrieval of a second value from the processing program counter. 
   
   
       24 . The system of  claim 23 , wherein the second value is retrieved from the program counter, transferred to the external device using the serial interface, and stored in a buffer on the external device. 
   
   
       25 . The system of  claim 22 , wherein the processing unit ceases automatically transmitting to the program counter in response to the external device no longer requesting values. 
   
   
       26 . The system of  claim 22 , further comprising a histogram analysis module external to the integrated device that applies a histogram algorithm on the value before storing the value in a buffer. 
   
   
       27 . The system of  claim 26 , wherein the histogram analysis module generates a histogram based on values from the program counter, the histogram generated at a same time the values are retrieved from the program counter. 
   
   
       28 . The system of  claim 26 , wherein the external device waits with reading new values from the program counter until the histogram analysis module finishes processing buffered values. 
   
   
       29 . A system comprising:
 a processing unit on an integrated device, the processing unit including a processing program counter to store an address for an instruction to be executed by the processing unit;   a debug program counter on the integrated device to receive the address from the processing unit upon the execution of the instruction by the processing unit; and   a serial interface to dynamically transfer a value from the debug program counter to a debugging device external to the integrated device while the processing unit is executing instructions;   wherein the processing unit halts execution, based on a halt instruction transmitted from the debugging device, before retrieval of a second value from the processing program counter.   
   
   
       30 . The system of  claim 29 , wherein the second value is retrieved from the debug program counter, transferred to the debugging device using the serial interface, and stored in a buffer on the debugging device. 
   
   
       31 . The system of  claim 29 , wherein the processing unit performs automatic value transmission to the debug program counter in response to a request from the debugging device, and wherein the processing unit ceases the automatic value transmission, while continuing to execute the instructions, in response to the debugging device no longer requesting values. 
   
   
       32 . The system of  claim 29 , further comprising a histogram analysis module external to the integrated device that applies a histogram algorithm on the value before storing the value in a buffer. 
   
   
       33 . The system of  claim 32 , wherein the histogram analysis module generates a histogram based on values from the debug program counter, the histogram generated at a same time the values are retrieved from the debug program counter. 
   
   
       34 . The system of  claim 32 , wherein the debugging device waits with reading new values from the debug program counter until the histogram analysis module finishes processing buffered values. 
   
   
       35 . A method comprising:
 executing, using a processing unit, instructions associated with respective program count values;   automatically transmitting, every time any of the instructions is executed, the program count value from a program count register accessible to the processing unit to a second register accessible to an external device; and   transmitting the program count value from the second register to the external device concurrently with the execution of the instructions.   
   
   
       36 . The method of  claim 35 , further comprising transmitting a second program count value from the second register and storing the second program count value in a buffer on the external device. 
   
   
       37 . The method of  claim 36 , further comprising transmitting an instruction to halt the processing unit before retrieval of the second program count value from the second register. 
   
   
       38 . The method of  claim 37 , further comprising outputting a second instruction associated with the second program count value. 
   
   
       39 . The method of  claim 35 , further comprising statistically analyzing program count values stored in a buffer on the external device to determine a time that the processing unit spends executing at least one of the instructions. 
   
   
       40 . The method of  claim 39 , further comprising applying a histogram algorithm on the program count value before storing the program count value in the buffer.