I2C: where is data from HAL_I2C_Master_Receive_IT()?

Garcia.Steve · ‎2016-01-08

Posted on January 08, 2016 at 23:50

Hi,

I'm attempting to read an I2C device withHAL_I2C_Master_Receive_IT(). A logic analyzer shows the data coming across the I2C bus, but where does it go? This is a st32f405, IAR, and CubeMx generated code. Given the logic analyzer results, it seems the I2C bus and CubeMx code is fundamentally working.

uint8_t value8;<
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><
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>value8 = 0x79;<
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>halResult = HAL_I2C_Master_Receive_IT(&hi2c1, (uint16_t)FUEL_GAUGE_I2C_ADDRESS, &value8, (uint16_t)1);<
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>

As I read the HAL documentation, the value read from I2C should be placed at value8. It's not. What am I missing? A more complete code block is below. The initial write is to configure the I2C slave for the following read. Everything appears correct on the logic analyzer.

uint16_t tmpValue;<
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> uint8_t value8;<
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> HAL_StatusTypeDef halResult;<
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> <
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> aTxBuffer[0] = 0x06; // cmd<
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> aTxBuffer[1] = 0x07; // cmd<
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> <
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> halResult = HAL_I2C_Master_Transmit_IT(&hi2c1, (uint16_t)FUEL_GAUGE_I2C_ADDRESS, (uint8_t*)&aTxBuffer[0], (uint16_t)2);<
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> if (halResult != HAL_OK)<
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> {<
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> return false;<
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> }<
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> <
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> // Wait for the end of the transfer<
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> //<
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> while (HAL_I2C_GetState(&hi2c1) != HAL_I2C_STATE_READY)<
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> {<
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> }<
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> <
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> HAL_Delay(70);<
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> <
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> // Read result<
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> //<
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> value8 = 0x79;<
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> <
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> halResult = HAL_I2C_Master_Receive_IT(&hi2c1, (uint16_t)FUEL_GAUGE_I2C_ADDRESS, &value8, (uint16_t)1);<
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> if (halResult != HAL_OK)<
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> {<
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> return false;<
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> }<
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><
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> tmpValue = (uint16_t)value8;<
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> *value = tmpValue;<
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> <
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> return true;<
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>

The result of this block is value8 remains unchanged by the call to HAL_I2C_Master_Receive_IT. I've tried various lengths for the I2C read and the result is consistent. Thre received data doesn't end up where the HAL documentation seems to say it should. Steve #stm32f405-hal-i2c

Garcia.Steve · ‎2016-01-08

Posted on January 08, 2016 at 23:55

Seems I didn't do too well with pasting the code blocks.

The first simple code block is:

uint8_t value8;

value8 = 0x79;

halResult = HAL_I2C_Master_Receive_IT(&hi2c1, (uint16_t)FUEL_GAUGE_I2C_ADDRESS, &value8, (uint16_t)1);

The larger code block is:

uint16_t tmpValue;

uint8_t value8;

HAL_StatusTypeDef halResult;

aTxBuffer[0] = 0x06; // cmd

aTxBuffer[1] = 0x07; // cmd

halResult = HAL_I2C_Master_Transmit_IT(&hi2c1, (uint16_t)FUEL_GAUGE_I2C_ADDRESS, (uint8_t*)&aTxBuffer[0], (uint16_t)2);

if (halResult != HAL_OK)

{

return false;

}

//Wait for the end of the transfer

//

while (HAL_I2C_GetState(&hi2c1) != HAL_I2C_STATE_READY)

{

}

HAL_Delay(70);

// Read result

//

value8 = 0x79;

halResult = HAL_I2C_Master_Receive_IT(&hi2c1, (uint16_t)FUEL_GAUGE_I2C_ADDRESS, &value8, (uint16_t)1);

if (halResult != HAL_OK)

{

return false;

}

tmpValue = (uint16_t)value8;

*value = tmpValue;

return true;

Tesla DeLorean · ‎2016-01-08

Posted on January 09, 2016 at 02:46

Be careful if the variable you are asking it to write under interrupt is a local/auto variable, in a routine you will leave.

If it's filling under interrupt, I presume the functions are non-blocking, and that the value will not be there until the interrupt actually occurs. You leave immediately, is it even done at that point?

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Garcia.Steve · ‎2016-01-08

Posted on January 09, 2016 at 04:59

Of course!

Thank you so much, Clive. I really appreciate it!

Steve