diff --git a/lesson-19/.ccsproject b/lesson-19/.ccsproject
index 4a356f6..255f3f5 100644
--- a/lesson-19/.ccsproject
+++ b/lesson-19/.ccsproject
@@ -1,15 +1,17 @@
+
-
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-
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diff --git a/lesson-19/.cproject b/lesson-19/.cproject
index 86d4696..f31749b 100644
--- a/lesson-19/.cproject
+++ b/lesson-19/.cproject
@@ -1,146 +1,171 @@
-
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@@ -148,7 +173,7 @@
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@@ -160,4 +185,5 @@
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\ No newline at end of file
diff --git a/lesson-19/README.md b/lesson-19/README.md
new file mode 100644
index 0000000..f21065a
--- /dev/null
+++ b/lesson-19/README.md
@@ -0,0 +1,32 @@
+Update for Code Composer Studio 11:
+-----------------------------------
+Code Composer Studio (CCS) 11 no longer comes with the GNU-ARM compiler.
+(Before that, CCS came bundled with the GNU-ARM Linaro toolchain).
+
+But CCS 11 can be easily configured to use other GNU-ARM toolchains, for
+example the GNU-ARM toolchain available from ARM-Developer website:
+
+https://developer.arm.com/open-source/gnu-toolchain/gnu-rm/downloads
+
+
+Changed CCS Project
+-------------------
+The CCS project in this lesson has been updated to use the GNU v10.3.1
+from the directory C:/qp/qtools/gnu_arm-none.eabi. This latter directory
+is the default location of installing the "QP-bundle", which contains
+the GNU-ARM toolchain.
+
+
+Adding an External GNU-ARM Compielr to CCS
+------------------------------------------
+However, you can also install the GNU-ARM compiler separately in any
+other directory. Then, you need to update the "Tool discovery path"
+in the Preferences dialog box.
+
+To open the Preferences dialog box, first select the "Project|Properties"
+menu and go to the Gneral section (on the left). In the "Compiler version"
+selection, click on the "More..." button.
+
+
+Quantum Leaps,
+2021-11-22
diff --git a/lesson-19/startup_tm4c_gnu.c b/lesson-19/startup_tm4c_gnu.c
index b6c6d40..9a02340 100644
--- a/lesson-19/startup_tm4c_gnu.c
+++ b/lesson-19/startup_tm4c_gnu.c
@@ -42,7 +42,7 @@
---------------------------------------------------------------------------*/
/* start and end of stack defined in the linker script ---------------------*/
-extern int __stack_start__;
+//extern int __stack_start__;
extern int __stack_end__;
/* Weak prototypes for error handlers --------------------------------------*/
@@ -59,7 +59,7 @@ __attribute__ ((naked)) void assert_failed(char const *module, int loc);
/* Function prototypes -----------------------------------------------------*/
void Default_Handler(void); /* Default empty handler */
void Reset_Handler(void); /* Reset Handler */
-void SystemInit(void); /* CMSIS system initialization */
+//void SystemInit(void); /* CMSIS system initialization */
/*----------------------------------------------------------------------------
* weak aliases for each Exception handler to the Default_Handler.
@@ -385,8 +385,8 @@ void Reset_Handler(void) {
software_init_hook(); /* this will also call __libc_init_array */
}
else {
- /* call all static constructors in C++ (harmless in C programs) */
- __libc_init_array();
+ /* call all static constructors in C++ (comment out in C programs) */
+ //__libc_init_array();
(void)main(); /* application's entry point; should never return! */
}
diff --git a/lesson-19/targetConfigs/Tiva TM4C123GH6PM.ccxml b/lesson-19/targetConfigs/Tiva TM4C123GH6PM.ccxml
index 0d8842e..c156333 100644
--- a/lesson-19/targetConfigs/Tiva TM4C123GH6PM.ccxml
+++ b/lesson-19/targetConfigs/Tiva TM4C123GH6PM.ccxml
@@ -1,13 +1,35 @@
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