Update documentation

Add documentation about how base addresses are used by the driver
unit tests.

Update message handler application to use TENSOR_ARENA_SIZE the
same way as the FreeRTOS application.

Add documenation about Corstone-310.

Change-Id: I08a315b95ca757ce3449cb7af104b8f1ac7f8865

4 files changed, 63 insertions, 84 deletions

diff --git a/README.md b/README.md
index 2c02a81..1efefec 100644
--- a/README.md
+++ b/README.md
@@ -54,7 +54,7 @@ $ cmake --build build
 It is also possible to build with a different toolchain.
 
 ```
-$ cmake -B build targets/corstone-300 -DCMAKE_TOOLCHAIN_FILE=$PWD/cmake/toolchain/arm-none-eabi-gcc.cmake
+$ cmake -B build targets/corstone-300 --toolchain $PWD/cmake/toolchain/arm-none-eabi-gcc.cmake
 $ cmake --build build
 ```
 
@@ -62,7 +62,7 @@ $ cmake --build build
 
 Building on a Windows host requires no special tools or shells, and can for
 example be done from a CMD prompt, Git Bash or from the CMake GUI. Only
-requirment is the build tools have been added to the path variable.
+requirement is the build tools have been added to the path variable.
 
 CMake supports a long list of generators, for example Ninja, NMake or Makefiles.
 For Windows Ninja has been verified to work well, but any of the supported
@@ -129,6 +129,23 @@ Same as above but for Ethos-U65 FVP.
 $ FVP_Corstone_SSE-300_Ethos-U65 -C ethosu.num_macs=512 applications/freertos/freertos.elf
 ```
 
+## Corstone-310 FVP
+
+Applications for the Corstone-310 FVP are built and tested similarly to the
+Corstone-300.
+
+```
+$ cmake -B build targets/corstone-310
+$ cmake --build build
+```
+
+Assuming the `FVP_Corstone_SSE-310` executable can be found via the PATH
+variable, the unit tests can be executed with `ctest`.
+
+```
+$ ctest --test-dir build
+```
+
 ## Corstone-300 MPS3 FPGA
 
 The files needed to get started for Corstone-300 can be found on
diff --git a/applications/driver_unit_tests/conv.cpp b/applications/driver_unit_tests/conv.cpp
index 63515fa..9e3dcc9 100644
--- a/applications/driver_unit_tests/conv.cpp
+++ b/applications/driver_unit_tests/conv.cpp
@@ -102,7 +102,7 @@ __attribute__((section(".sram.data"), aligned(16))) char commandStream[] = {
     0x00, 0x00, 0xff, 0xff,                          // cmd0.NPU_OP_STOP                  65535   -
 }; // clang-format on
 
-__attribute__((section(".sram.data"), aligned(16))) char weightsBiases0[] = {
+__attribute__((section(".sram.data"), aligned(16))) char tflmModel[] = {
     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x22, 0xa4, 0x7b, 0x26, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x22, 0xa4, 0x7b,
     0x26, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf0, 0x00, 0x5c, 0xe6, 0x4d, 0xf9, 0xef, 0x6f, 0xcf,
@@ -111,74 +111,7 @@ __attribute__((section(".sram.data"), aligned(16))) char weightsBiases0[] = {
     0x4f, 0xbb, 0x39, 0x01, 0x08, 0x9e, 0x96, 0x87, 0xff, 0xff, 0xff, 0x0f, 0x00, 0x00, 0x4c, 0x35, 0x30, 0x89, 0x1d,
     0x00, 0xe0, 0xfc, 0xff, 0xbf, 0x1f, 0xfc, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
 
-__attribute__((section(".sram.data"), aligned(16))) char scratch[] = {
-    0xac, 0x0a, 0x7f, 0x8c, 0x2f, 0xaa, 0xc4, 0x97, 0x75, 0xa6, 0x16, 0xb7, 0xc0, 0xcc, 0x21, 0xd8, 0x43, 0xb3, 0x4e,
-    0x9a, 0xfb, 0x52, 0xa2, 0xdb, 0xc3, 0x76, 0x7d, 0x8b, 0x67, 0x7d, 0xe5, 0xd8, 0x09, 0xa4, 0x74, 0x6c, 0xd3, 0xde,
-    0xa1, 0x9f, 0x15, 0x51, 0x59, 0xa5, 0xf2, 0xd6, 0x66, 0x62, 0x24, 0xb7, 0x05, 0x70, 0x57, 0x3a, 0x2b, 0x4c, 0x46,
-    0x3c, 0x4b, 0xe4, 0xd8, 0xbd, 0x84, 0x0e, 0x58, 0x9a, 0xb2, 0xf6, 0x8c, 0xcd, 0xcc, 0x45, 0x3a, 0x39, 0x29, 0x62,
-    0xc1, 0x42, 0x48, 0x7a, 0xe6, 0x7d, 0xae, 0xca, 0x27, 0x4a, 0xea, 0xcf, 0x57, 0xa8, 0x65, 0x87, 0xae, 0xc8, 0xdf,
-    0x7a, 0x58, 0x5e, 0x6b, 0x91, 0x51, 0x8b, 0x8d, 0x64, 0xa5, 0xe6, 0xf3, 0xec, 0x19, 0x42, 0x09, 0xd6, 0x4d, 0x6b,
-    0x2f, 0x12, 0x48, 0x98, 0x5f, 0x56, 0x09, 0x1b, 0x4e, 0x16, 0x94, 0x97, 0xee, 0xa5, 0x73, 0x08, 0x2d, 0x05, 0xd0,
-    0x13, 0x45, 0x5e, 0xf3, 0x92, 0x26, 0xd5, 0xc5, 0x1e, 0x08, 0xf5, 0xfe, 0x47, 0x35, 0xc7, 0x4f, 0x07, 0xee, 0x23,
-    0xaf, 0x1d, 0xb9, 0xde, 0xc0, 0x09, 0xbe, 0xde, 0x52, 0xbb, 0x86, 0xfa, 0x63, 0x60, 0x3e, 0x79, 0xd8, 0xa7, 0x95,
-    0xcc, 0xb1, 0x7c, 0x08, 0xcd, 0xf3, 0x82, 0x23, 0x76, 0x1d, 0x03, 0x3e, 0x85, 0x93, 0xc2, 0xd0, 0xc7, 0x93, 0x0c,
-    0xcb, 0xad, 0x8e, 0x3b, 0x47, 0x1e, 0xa7, 0x61, 0x7b, 0xb8, 0x20, 0xdd, 0xd1, 0xa3, 0xc1, 0x3f, 0xff, 0x94, 0x09,
-    0xcd, 0xb2, 0x24, 0xb9, 0x4a, 0x91, 0x89, 0x7f, 0xd2, 0xd5, 0xf1, 0x20, 0xa2, 0x34, 0xc2, 0x1f, 0xda, 0x97, 0x85,
-    0xca, 0xc2, 0x1c, 0x1b, 0xf4, 0x48, 0x27, 0x6a, 0x97, 0xe0, 0x3d, 0x79, 0xa3, 0xea, 0xb9, 0x43, 0xfe, 0x79, 0xb3,
-    0x2f, 0xcb, 0x2d, 0x34, 0xc6, 0x72, 0xab, 0xa6, 0xbc, 0xb7, 0x44, 0xc6, 0x74, 0x1c, 0xd8, 0x6f, 0x37, 0x22, 0xe3,
-    0x84, 0x91, 0x80, 0xa8, 0x9d, 0x22, 0x80, 0x68, 0xcf, 0x04, 0xa4, 0xe7, 0xfa, 0x52, 0x35, 0x5c, 0x1d, 0x9e, 0x85,
-    0x17, 0x51, 0x26, 0x26, 0x4e, 0xb2, 0x9c, 0xe8, 0x0d, 0xea, 0x38, 0xf4, 0x62, 0xef, 0x9d, 0x11, 0xf1, 0xf0, 0x62,
-    0x4f, 0x79, 0x99, 0xf1, 0x84, 0xb1, 0x10, 0xe7, 0x69, 0xc6, 0x8b, 0xae, 0x2a, 0xec, 0x2f, 0x73, 0xba, 0xb5, 0x08,
-    0x5c, 0x1f, 0xba, 0xf1, 0x9c, 0x78, 0x53, 0xe1, 0x6f, 0x01, 0x51, 0x00, 0xe7, 0x41, 0xf5, 0x97, 0xb2, 0xe7, 0x6f,
-    0x6a, 0x19, 0xa9, 0xef, 0x6a, 0x0f, 0x39, 0x68, 0x45, 0xf8, 0x23, 0x39, 0xb1, 0xaa, 0x66, 0x2f, 0x34, 0xa7, 0x77,
-    0xec, 0xae, 0xab, 0x0b, 0xbb, 0xc0, 0x2b, 0xae, 0xa1, 0xdb, 0x35, 0x52, 0xdc, 0xaf, 0x5b, 0x5b, 0x50, 0x01, 0x21,
-    0x80, 0xf7, 0x2c, 0xc0, 0x8e, 0xe9, 0xbf, 0x50, 0x63, 0xca, 0x9a, 0x9b, 0x35, 0x26, 0x1c, 0x5d, 0x8c, 0x4b, 0x36,
-    0x53, 0x79, 0x6a, 0xf8, 0x91, 0xaa, 0x3f, 0xd6, 0x09, 0x54, 0x30, 0x48, 0x70, 0xcb, 0xc8, 0x5f, 0xa2, 0x44, 0x11,
-    0x06, 0xfd, 0x06, 0xb3, 0x7d, 0xf5, 0xc4, 0x9b, 0x1f, 0x1a, 0x2f, 0x44, 0x1d, 0xa7, 0x7f, 0xf2, 0x78, 0x35, 0xf4,
-    0x37, 0x93, 0xa2, 0x83, 0x94, 0x4b, 0x29, 0xcc, 0xf3, 0xcb, 0xfe, 0x64, 0x1b, 0x32, 0xa7, 0xb4, 0x24, 0xf4, 0x94,
-    0xe8, 0xb7, 0xd7, 0x40, 0x4e, 0x0f, 0x14, 0x6a, 0x8f, 0x24, 0x60, 0x77, 0x94, 0xc6, 0x85, 0x79, 0xe3, 0xac, 0x92,
-    0x3e, 0xba, 0x5b, 0x9e, 0x9f, 0x17, 0x3b, 0xb2, 0x28, 0xcf, 0xaa, 0x87, 0x56, 0x8d, 0x8b, 0x41, 0x1c, 0x75, 0x91,
-    0xbc, 0xac, 0x55, 0x37, 0x05, 0xa8, 0x30, 0x22, 0x34, 0x51, 0x31, 0xf5, 0x5f, 0x23, 0x45, 0xa6, 0x41, 0xc7, 0xa9,
-    0x38, 0x53, 0x32, 0xa3, 0x16, 0x17, 0xf3, 0xc0, 0xc5, 0x64, 0x5e, 0x5f, 0x5c, 0x9b, 0xa9, 0xc5, 0x9c, 0x2c, 0xd2,
-    0x5e, 0x6e, 0x79, 0x03, 0x00, 0xa1, 0xdb, 0x18, 0x71, 0xd7, 0x72, 0x9f, 0xb2, 0x8e, 0x83, 0xd6, 0x24, 0xf5, 0x74,
-    0xac, 0xa2, 0xe7, 0x99, 0x18, 0x30, 0x63, 0xd1, 0xf8, 0x5d, 0x3f, 0xf9, 0xf9, 0x83, 0x49, 0xd1, 0xe0, 0x62, 0x86,
-    0xf9, 0x77, 0x2a, 0xbe, 0x76, 0x82, 0xcd, 0x03, 0x0d, 0xfa, 0x70, 0x51, 0x43, 0x0e, 0xe7, 0x27, 0xd7, 0x9a, 0x95,
-    0x2b, 0x7f, 0x73, 0xc9, 0x60, 0x40, 0xbd, 0x7f, 0xe9, 0x1d, 0x05, 0x00, 0x36, 0x08, 0x0a, 0x8a, 0xf7, 0x13, 0x71,
-    0x72, 0x09, 0x66, 0x48, 0x2b, 0x32, 0xc6, 0xfa, 0xba, 0x33, 0xc5, 0x1e, 0x7f, 0x8d, 0x04, 0x5c, 0x17, 0xd8, 0xcf,
-    0x4b, 0xbb, 0xd6, 0x1b, 0x7b, 0x82, 0xf0, 0x64, 0x1e, 0x79, 0x19, 0x4c, 0xb0, 0x62, 0x58, 0x67, 0x51, 0x3e, 0xde,
-    0x66, 0xe1, 0xa3, 0x23, 0x0d, 0x6a, 0xde, 0x7a, 0x11, 0xeb, 0x7b, 0xf8, 0x6b, 0x10, 0xc3, 0xa7, 0x81, 0x37, 0x52,
-    0xda, 0x45, 0xb1, 0xae, 0x37, 0xb0, 0x90, 0xe3, 0xca, 0x0c, 0x91, 0x94, 0x5c, 0x77, 0xdd, 0xd1, 0x90, 0xf0, 0x43,
-    0x32, 0xca, 0x4b, 0x82, 0x9b, 0x95, 0xf3, 0x85, 0x0e, 0x5b, 0xae, 0xea, 0x29, 0x7c, 0x0c, 0x18, 0x3a, 0xfc, 0xd0,
-    0xeb, 0xc1, 0x3a, 0x71, 0x93, 0x24, 0xdc, 0x46, 0x15, 0x0a, 0x5b, 0xe6, 0xed, 0x56, 0x90, 0x18, 0x47, 0x2b, 0xbc,
-    0x8d, 0x51, 0x68, 0x33, 0x65, 0x02, 0x0b, 0x68, 0xdb, 0xaa, 0x02, 0xbb, 0xa3, 0xd7, 0x33, 0x81, 0xbd, 0x21, 0x50,
-    0x34, 0xad, 0xa5, 0x20, 0x38, 0x61, 0xb7, 0xb6, 0x14, 0x65, 0xd7, 0x80, 0x84, 0x16, 0x4a, 0x26, 0x5b, 0xc5, 0x43,
-    0x13, 0xa1, 0xe5, 0x2e, 0xae, 0x94, 0xd7, 0x65, 0x2a, 0xb6, 0x25, 0x96, 0x73, 0xb5, 0x85, 0x8d, 0xb8, 0xc4, 0x25,
-    0x05, 0xbc, 0x89, 0x39, 0x2a, 0xe8, 0x69, 0x35, 0xd4, 0x4d, 0xbe, 0xab, 0x5e, 0x1e, 0xb9, 0x33, 0x01, 0x18, 0x35,
-    0x7d, 0x25, 0x7d, 0x62, 0x85, 0xad, 0x02, 0x83, 0xd2, 0x91, 0x03, 0x3e, 0x1f, 0x45, 0x5e, 0x20, 0x28, 0xb4, 0xe2,
-    0xac, 0x35, 0xbc, 0x6b, 0x97, 0xd9, 0x49, 0x0d, 0xfd, 0x51, 0xf6, 0x70, 0xf7, 0xeb, 0x6e, 0x28, 0x49, 0xae, 0x3f,
-    0x48, 0x35, 0x90, 0xc1, 0x13, 0x0c, 0x7f, 0x93, 0x5f, 0xb2, 0x66, 0x65, 0x48, 0x0f, 0x90, 0x97, 0x9a, 0xc5, 0x62,
-    0xe5, 0xc2, 0x19, 0x7f, 0x92, 0xf8, 0x54, 0x90, 0xa3, 0xb4, 0xe0, 0x1b, 0x39, 0x43, 0xe9, 0x3c, 0xe4, 0xec, 0x5b,
-    0xe7, 0xf3, 0x3d, 0x1f, 0x18, 0xae, 0x0e, 0xcf, 0x76, 0x72, 0x60, 0x9f, 0xfe, 0x72, 0x04, 0x3d, 0xae, 0xd8, 0xc3,
-    0x9f, 0x83, 0xfa, 0xed, 0x12, 0x11, 0xb3, 0x8b, 0x68, 0xbf, 0x1d, 0xfc, 0xd3, 0x24, 0x4c, 0x56, 0xaa, 0x5b, 0xc4,
-    0xcd, 0x0d, 0x55, 0xd0, 0x79, 0x0b, 0x6d, 0x69, 0x6d, 0x66, 0x81, 0x65, 0x4b, 0x93, 0xe9, 0xac, 0xb8, 0xfa, 0x8f,
-    0xe1, 0x10, 0xa6, 0xf2, 0x3f, 0x98, 0x4c, 0xce, 0x94, 0x9d, 0x13, 0x2f, 0x50, 0x95, 0x68, 0xb9, 0xe1, 0x6e, 0x84,
-    0x25, 0xf7, 0x19, 0xc0, 0x49, 0xb1, 0xd0, 0xa5, 0xa5, 0x96, 0xbc, 0x43, 0xaa, 0xb9, 0x79, 0x07, 0xe0, 0xa8, 0x76,
-    0xcb, 0x56, 0x80, 0x75, 0x34, 0x80, 0x88, 0xbd, 0xe5, 0xc1, 0xf4, 0x53, 0x36, 0x04, 0x3b, 0xa1, 0x8a, 0xdc, 0xa4,
-    0x68, 0x27, 0x16, 0x65, 0xa0, 0xc3, 0x81, 0x6c, 0xe4, 0x3c, 0x6a, 0x9e, 0xfb, 0x95, 0x3c, 0x9b, 0xfb, 0xea, 0x90,
-    0x79, 0x79, 0xd8, 0xe9, 0x04, 0x46, 0x95, 0x5a, 0x78, 0xd5, 0x01, 0x34, 0x4d, 0x1f, 0xa9, 0x50, 0xb7, 0x00, 0x00,
-    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
-
-__attribute__((section(".sram.data"), aligned(16))) char fastScratch[] = {
+__attribute__((section(".sram.data"), aligned(16))) char tflmArena[] = {
     0xac, 0x0a, 0x7f, 0x8c, 0x2f, 0xaa, 0xc4, 0x97, 0x75, 0xa6, 0x16, 0xb7, 0xc0, 0xcc, 0x21, 0xd8, 0x43, 0xb3, 0x4e,
     0x9a, 0xfb, 0x52, 0xa2, 0xdb, 0xc3, 0x76, 0x7d, 0x8b, 0x67, 0x7d, 0xe5, 0xd8, 0x09, 0xa4, 0x74, 0x6c, 0xd3, 0xde,
     0xa1, 0x9f, 0x15, 0x51, 0x59, 0xa5, 0xf2, 0xd6, 0x66, 0x62, 0x24, 0xb7, 0x05, 0x70, 0x57, 0x3a, 0x2b, 0x4c, 0x46,
@@ -315,22 +248,42 @@ char expected0[] = {0x00, 0xff, 0x00, 0xff, 0x00, 0xff, 0x00, 0xff, 0x00, 0xff,
  ****************************************************************************/
 
 int main() {
-    CommandStream cs(DataPointer(commandStream, sizeof(commandStream)),
-                     BasePointers({DataPointer(weightsBiases0, sizeof(weightsBiases0)),
-                                   DataPointer(scratch, sizeof(scratch)),
-                                   DataPointer(fastScratch, sizeof(fastScratch))}),
-                     PmuEvents({ETHOSU_PMU_CYCLE, ETHOSU_PMU_NPU_IDLE, ETHOSU_PMU_NPU_ACTIVE}));
+    /*
+     * The command stream compiled by Vela only uses two base addresses (for a
+     * network without fast scratch).
+     *
+     * The first base address points at the TFLM model. This buffer contains
+     * constant data, like the command stream, weights and biases.
+     *
+     * The second base address points at the TFLM arena. This buffer contains
+     * variable data, like the IFM, OFM, activations etc.
+     *
+     * NOTE! Really important to understand is that the command stream will
+     * access the IFM and OFM buffers using the second base address only.
+     * Consequently the input- and output pointers below are referring to an
+     * offset within the TFLM arena.
+     *
+     * NOTE! The offsets of the IFM and OFM buffers within the TFLM arena
+     * varies between models. They can be found comparing input tensor 4 and
+     * output tensor 0 with the address of the TFLM arena.
+     *
+     * The remaining base addresses are unused.
+     */
+    CommandStream cs(
+        DataPointer(commandStream, sizeof(commandStream)),
+        BasePointers({DataPointer(tflmModel, sizeof(tflmModel)), DataPointer(tflmArena, sizeof(tflmArena))}),
+        PmuEvents({ETHOSU_PMU_CYCLE, ETHOSU_PMU_NPU_IDLE, ETHOSU_PMU_NPU_ACTIVE}));
 
     const size_t repeat = 100;
     uint64_t cycleCount = 0;
     int errors          = 0;
     int res;
 
-    // Input data located inside the scratch buffer
-    DataPointer inputPointer(scratch, sizeof(input0));
+    // Input data located inside the arena
+    DataPointer inputPointer(tflmArena, sizeof(input0));
 
-    // Output data located inside the scratch buffer
-    DataPointer outputPointer(scratch + 1024, sizeof(expected0));
+    // Output data located inside the arena
+    DataPointer outputPointer(tflmArena + 1024, sizeof(expected0));
 
     // Expected output data
     DataPointer expectedPointer(expected0, sizeof(expected0));
diff --git a/applications/message_handler/CMakeLists.txt b/applications/message_handler/CMakeLists.txt
index 3f87e64..040b27d 100644
--- a/applications/message_handler/CMakeLists.txt
+++ b/applications/message_handler/CMakeLists.txt
@@ -21,7 +21,7 @@ if (NOT TARGET freertos_kernel)
     return()
 endif()
 
-set(MESSAGE_HANDLER_ARENA_SIZE 2000000 CACHE STRING "Size of message handler tensor arena")
+set(MESSAGE_HANDLER_ARENA_SIZE 2000000 CACHE STRING "Total size of all message handler tensor arenas")
 set(MESSAGE_HANDLER_MODEL_0 FALSE CACHE STRING "Path to built in model 0")
 set(MESSAGE_HANDLER_MODEL_1 FALSE CACHE STRING "Path to built in model 1")
 set(MESSAGE_HANDLER_MODEL_2 FALSE CACHE STRING "Path to built in model 2")
@@ -42,8 +42,17 @@ ethosu_add_executable(message_handler
 target_include_directories(message_handler PRIVATE
     ${LINUX_DRIVER_STACK_PATH}/kernel)
 
+# Split total tensor arena equally for each NPU
+if (TARGET ethosu_core_driver AND ETHOSU_TARGET_NPU_COUNT GREATER 0)
+    set(NUM_ARENAS ${ETHOSU_TARGET_NPU_COUNT})
+else()
+    set(NUM_ARENAS 1)
+endif()
+
+math(EXPR TENSOR_ARENA_SIZE "${MESSAGE_HANDLER_ARENA_SIZE} / ${NUM_ARENAS}")
+
 target_compile_definitions(message_handler PRIVATE
-    TENSOR_ARENA_SIZE=${MESSAGE_HANDLER_ARENA_SIZE}
+    TENSOR_ARENA_SIZE=${TENSOR_ARENA_SIZE}
     $<$<BOOL:${MESSAGE_HANDLER_MODEL_0}>:MODEL_0=${MESSAGE_HANDLER_MODEL_0}>
     $<$<BOOL:${MESSAGE_HANDLER_MODEL_1}>:MODEL_1=${MESSAGE_HANDLER_MODEL_1}>
     $<$<BOOL:${MESSAGE_HANDLER_MODEL_2}>:MODEL_2=${MESSAGE_HANDLER_MODEL_2}>
diff --git a/applications/message_handler/main.cpp b/applications/message_handler/main.cpp
index b527840..8db9e0b 100644
--- a/applications/message_handler/main.cpp
+++ b/applications/message_handler/main.cpp
@@ -52,14 +52,14 @@ using namespace MessageHandler;
  ****************************************************************************/
 
 // Nr. of tasks to process inferences with, reserves driver & runs inference (Normally 1 per NPU, but not a must)
-#if defined(ETHOSU_NPU_COUNT)
+#if defined(ETHOSU) && defined(ETHOSU_NPU_COUNT) && ETHOSU_NPU_COUNT > 0
 constexpr size_t NUM_PARALLEL_TASKS = ETHOSU_NPU_COUNT;
 #else
 constexpr size_t NUM_PARALLEL_TASKS = 1;
 #endif
 
 // TensorArena static initialisation
-constexpr size_t arenaSize = TENSOR_ARENA_SIZE / NUM_PARALLEL_TASKS;
+constexpr size_t arenaSize = TENSOR_ARENA_SIZE;
 
 __attribute__((section(".bss.tensor_arena"), aligned(16))) uint8_t tensorArena[NUM_PARALLEL_TASKS][arenaSize];