# When doing the book examples I used a different p24 mcu and have errors **URL:** \ **Category:** Kernel\ **Created:** [September 8, 2019, 7:45pm UTC](https://forums.freertos.org/t/when-doing-the-book-examples-i-used-a-different-p24-mcu-and-have-errors/8048 "2019-09-08T19:45:36Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![system](https://d2v6vdsk2p900z.cloudfront.net/original/1X/7fc8fdb729c645aab5b20282bbe34e57cb407be6.jpeg) [@system](https://forums.freertos.org/u/system)\ **Post date:** [September 8, 2019, 7:45pm UTC](https://forums.freertos.org/t/when-doing-the-book-examples-i-used-a-different-p24-mcu-and-have-errors/8048/1 "2019-09-08T19:45:36Z")
**[gatolen](https://sourceforge.net/u/gatolen/)** wrote on [Sunday, September 08, 2019](https://sourceforge.net/p/freertos/discussion/382005/thread/a068a83964/#e9db): Hi, I have enjoyed FreeRTOS and have a program currently working fine. I decided to go thru the book examples again with p different pic24. Now after changing the new config files for the different chip all builds fine except at the end of the building process I have errors in a couple header files (related to timers.o, tasks.o, queue.o,) which has undefined reference to \_vPortFree, \_pvPortMalloc functions. How do I correct this with this new chip? Thank you very much, Len ---
**Author:** ![rtel](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/rtel/32/31_2.png) [@rtel](https://forums.freertos.org/u/rtel)\ **Post date:** [September 8, 2019, 8:27pm UTC](https://forums.freertos.org/t/when-doing-the-book-examples-i-used-a-different-p24-mcu-and-have-errors/8048/2 "2019-09-08T20:27:24Z")
**[rtel](https://sourceforge.net/u/rtel/)** wrote on [Sunday, September 08, 2019](https://sourceforge.net/p/freertos/discussion/382005/thread/a068a83964/#3c5b): Those functions are defined in the heap implementations, so you need to include one of heap\_1 to heap\_5 in the project too [https://www.freertos.org/a00111.html](https://www.freertos.org/a00111.html)