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November 28, 2023
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How to access STM8 cpu registers

  • November 28, 2023
  • 1 reply
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Hello

How can I access STM8S CPU registers (Cosmic compiler)? When I write this "A = 0xff" (A is a processor register accumulator), then compiler writes this "#error cpstm8 main.c:17(3) A undefined". How to fix it?

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    Best answer by mƎALLEm

    Hello,

    You need to access internal CPU registers with assembly language. You can insert asm code inside C code.

    See https://www.cosmicsoftware.com/pdf/cxstm8_pd.pdf / page 2.

    PS: this thread is the duplication of this one: https://community.st.com/t5/stm8-mcus/stm8-cpu-register-cosmic/td-p/614181

    1 reply

    mƎALLEmAnswer
    Technical Moderator
    November 28, 2023

    Hello,

    You need to access internal CPU registers with assembly language. You can insert asm code inside C code.

    See https://www.cosmicsoftware.com/pdf/cxstm8_pd.pdf / page 2.

    PS: this thread is the duplication of this one: https://community.st.com/t5/stm8-mcus/stm8-cpu-register-cosmic/td-p/614181