problem map a struct to Backup registers

jgnoss · ‎2013-04-01

Posted on April 01, 2013 at 11:06

I got a problem map a struct to Backup registers

what I do is:

/******************************************************************************************/

typedef struct {

uint16_t actPageNo;

uint16_t sollQTY;

uint16_t lcd_BackLight;

uint16_t lcd_Contrast;

uint16_t rpm_Ticks;

uint8_t actProfile;

uint8_t dummy;

} processData_t;

#define ProcessData ((processData_t *)(RTC_BASE + 0x50))

void init_ProcessData(void){

init_RTC();

}

void processData_SetDefaultValues(void){

ProcessData->actPageNo = 1;

ProcessData->sollQTY = 200;

ProcessData->lcd_BackLight = 5000;

ProcessData->lcd_Contrast = 750;

ProcessData->rpm_Ticks = 512;

ProcessData->actProfile = 16;

ProcessData->dummy = 0;

};

processData_SetDefaultValues();

uint32_t r = 0;

uint8_t t = 0;

for (t = 0; t < 5; t++) {

r = RTC_ReadBackupRegister(t);

tfp_sprintf(ss,''\r\nbefore %d = %u %X\r\n'', t,r, r);

uart1_puts(ss);

}

tfp_sprintf(ss,''\r\nbefore aPro %d aPa %u sPa %u B %u C %u \r\n'',

ProcessData->actProfile,

ProcessData->actPageNo,

ProcessData->sollQTY,

ProcessData->lcd_BackLight,

ProcessData->lcd_Contrast

);

uart1_puts(ss);

r = (5000 << 16) | 750;

RTC_WriteBackupRegister(RTC_BKP_DR1, r);

for (t = 0; t < 5; t++) {

r = RTC_ReadBackupRegister(t);

tfp_sprintf(ss,''\r\nafter %d = %u %X\r\n'', t,r, r);

uart1_puts(ss);

}

tfp_sprintf(ss,''\r\nafter aPro %d aPa %u sPa %u B %u C %u \r\n'',

ProcessData->actProfile,

ProcessData->actPageNo,

ProcessData->sollQTY,

ProcessData->lcd_BackLight,

ProcessData->lcd_Contrast );

uart1_puts(ss);

/******************************************************************************************/

but result while setting values using the struct is not as expected:

before 0 = 13107400 C800C8

before 1 = 49152750 2EE02EE

before 2 = 0 0

before 3 = 0 0

before 4 = 0 0

before aPro 0 aPa 200 sPa 200 B 750 C 750

while building my own 32Bit value and writing it to the register

using StdPerphLib function and read the data back using struct works just fine

after 0 = 13107400 C800C8

after 1 = 327680750 138802EE

after 2 = 0 0

after 3 = 0 0

after 4 = 0 0

after aPro 0 aPa 200 sPa 200 B 750 C 5000

I use codesourcery toolchain

Any idea what's happening there?

Tesla DeLorean · ‎2013-04-01

Posted on April 01, 2013 at 13:42

What packing is being used here? Does the sizeof() match your expectation? Look at how it works on a RAM address, in the debugger. Look at the assembler code generated.

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jgnoss · ‎2013-04-01

Posted on April 01, 2013 at 15:40

Thank's clive1,

Packing is off, and sizeof() returns the correct size.

On another place in the same program I use another structure to write page aligned in an eeprom.

I didn't go in and learn about the ARM assembler instructions yet, assembler I'm not the hero, but as far as I can go with it, it seams to be correct.

08001230 <processData_SetDefaultValues>:

8001230: 4b08 ldr r3, [pc, #32] ; (8001254 <processData_SetDefaultValues+0x24>)

8001232: 2201 movs r2, #1

8001234: 801a strh r2, [r3, #0]

8001236: 20c8 movs r0, #200 ; 0xc8

8001238: 4907 ldr r1, [pc, #28] ; (8001258 <processData_SetDefaultValues+0x28>)

800123a: 4a08 ldr r2, [pc, #32] ; (800125c <processData_SetDefaultValues+0x2c>)

800123c: 8058 strh r0, [r3, #2]

800123e: 2080 movs r0, #128 ; 0x80

8001240: 8099 strh r1, [r3, #4]

8001242: 80da strh r2, [r3, #6]

8001244: 0081 lsls r1, r0, #2

8001246: 2210 movs r2, #16

8001248: 2000 movs r0, #0

800124a: 8119 strh r1, [r3, #8]

800124c: 729a strb r2, [r3, #10]

800124e: 72d8 strb r0, [r3, #11]

8001250: 4770 bx lr

8001252: 46c0 nop ; (mov r8, r8)

8001254: 40002850 .word 0x40002850

8001258: 00001388 .word 0x00001388

800125c: 000002ee .word 0x000002ee

Tesla DeLorean · ‎2013-04-01

Posted on April 01, 2013 at 16:15

While not explicitly stated, I'd be concerned that the memory doesn't perform write granularity below 32-bits. ie It's a register, not a memory with selective byte write lanes/selects.

Try this approach:

void processData_SetDefaultValues(void)
{
processData_t pd;
uint32_t *src, *dst;
int i = (sizeof(pd) + 3) / 4; // Size rounded to 32-bit words
// Perform localized initialization, and do a 32-bit wide copy
pd.actPageNo = 1;
pd.sollQTY = 200;
pd.lcd_BackLight = 5000;
pd.lcd_Contrast = 750;
pd.rpm_Ticks = 512;
pd.actProfile = 16;
pd.dummy = 0;
src = (uint32_t *)&pd;
dst = (uint32_t *)(RTC_BASE + 0x50); // RTC_BKPxR
while(i--)
*dst++ = *src++;
}

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dthedens23 · ‎2013-04-01

Posted on April 01, 2013 at 16:31

perhaps Printf is confused about what it is being asked to print because of the #define.

and because of things like actProfile being a char and being told to print like a 32bit %d

I use ''placement new'' in C++ but I think this should work in C

processData_t * ProcessData = ((processData_t *)(RTC_BASE + 0x50));

forgive my stupidity, it's Monday. But it may still be a type related issue caused by the define.

jgnoss · ‎2013-04-01

Posted on April 01, 2013 at 17:05

@rocketdawg

printf is not the problem, see second part of my example from first post.

The problem doesn't appear on reading the regs using a struct,

just on writing it goes wrong.

@clive1

Sorry I didn't say what controller it is. It's a STM32F051.

Yes writing the 32Bit regs entirely works perfect.

I tried to make the access to this regs more elegant, because I like to hold process critical data in it, which I like to have present also after a power fail. And that registers are heavily accessed.

So I have to do it by hand again.

Thank's clive1

Ju

jgnoss · ‎2013-04-01

Posted on April 01, 2013 at 17:10

@rocketdawg

just read the edit in your post.

We accept the Monday-excuse ;)

Ju

Tesla DeLorean · ‎2013-04-01

Posted on April 01, 2013 at 17:55

A reasonable abstraction might be to hold the current/working data in a copy of the registers, and then a routine to flush to the NV memory of choice when you change the copy. A RAM based copy should also be faster.

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