MCU (such as Cortex M0+ based on Cortex V6M, etc.) Code usually runs in embedded Flash. In some specific applications, some functions need to be run in RAM. In order to solve this problem, a solution method is implemented. The specific method is as follows:
1. Realize the routine to run in RAM. This routine is implemented in pure assembly, such as:
__asm ​​void program_word2addr(uint32_t addr, uint32_t data)
{
push {r3, r4, r5, lr} ;save some regsiters
/*your code for this rouTIne*/
pop {r3, r4, r5, pc}
}
2. When compiling, use the compile option whose code has nothing to do with the running position, such as (Keil --apcs /ropi/rwpi), to generate *.axf;
3. Use fromelf -c to generate *.axf disassembly, find the corresponding program_word2addr implementation part, and copy the binary code corresponding to rouTIne to the code to be applied, in the form of a read-only array:
Such as:
const staic uint16_t s_flashProg2AddressCode[16] = {...., ....}
4. Define a global array, such as staTIc uint16_t g_code[16], size is exactly equal to
The length of s_flashProg2AddressCode;
5. Define a function pointer, such as static void (*callFlashPrg2Address)(uint32_t addr, uint32_t data)
6. Define a function to run Code with RAM, such as:
void run_prgcode_onram(uint32_t addr, uint32_t data)
{
memcpy(g_code,s_flashProg2AddressCode,32 );
callFlashPrg2Address = (void (*)(uint32_t addr, uint32_t data))((uin32_t)g_code + 1);
callFlashPrg2Address (address, data);
}
run_prgcode_onram, you can run program_word2addr in RAM.
callFlashPrg2Address = (void (*)(uint32_t addr, uint32_t data))((uin32_t)g_code + 1); The purpose of +1, because the operating platform is Cortex V6M, the thumb instruction set used is completed according to the requirements of the ARM Spec.
callFlashPrg2Address (address, data); is the key to realize RAM running program_word2addr.
Rectifier bridge is to seal the rectifier tube in a shell. Points full bridge and half bridge. The full bridge connects the four diodes of the connected bridge rectifier circuit together. The half bridge is half of four diode bridge rectifiers, and two half bridges can be used to form a bridge rectifier circuit. One half bridge can also be used to form a full-wave rectifier circuit with a center-tapped transformer. Select a rectifier bridge to consider. Rectifier circuit and operating voltage.
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