Hello.
My tests were based on the sample project "adc_demo" of the IAR directory (C:\Program Files\IAR Systems\Embedded Workbench 6.5\arm\examples\Freescale\Kinetis\adc_demo).
This example make the measurement of the potentiometer on the ADC1_DM1 channel, as shown below:
When the potentiometer is at 0V position (I also put the ADC1_DM1 pin on GND to make sure that the value is 0V), I have unstable measurements of this ADC channel after a reset (either at reset button SW3, or reset by IAR software).
Below the stable measurement:
After the reset, we have the following values, with a wide variation in R1B (potentiometer channel):
After a few more resets it back to be stable.
In the original example of IAR, only made some small modifications, such as:
- PMC_REGSC |= 1; // To enable the bandgap buffer to read bandgap value.
- Master_Adc_Config.STATUS1A = AIEN_ON | DIFF_SINGLE | ADC_SC1_ADCH(0x1B); // Bandgap Read in ADC0_RA.
- Master_Adc_Config.STATUS1B = AIEN_ON | DIFF_SINGLE | ADC_SC1_ADCH(0x1B); // Vrefsh read in ADC0_RB.
- Master_Adc_Config.STATUS1A = AIEN_ON | DIFF_SINGLE | ADC_SC1_ADCH(0x1E); // Vrefsl read in ADC1_RA.
- Master_Adc_Config.STATUS1B = AIEN_ON | DIFF_SINGLE | ADC_SC1_ADCH(ADC1_CHANB); // Potentiometer read.
- printf("Bandgap=%6d VREFSH=%6d VREFSL=%6d R1B=%6d\r\n", result0A,result0B,result1A,result1B); // To show the results in console (UART).
The sample project is attached.
Original Attachment has been moved to: adc_demo.zip
Hi,
There are two tower boards for K60 product. TWR-K60D100M and TWR-K60N512 boards, which board you are testing with?
Have a great day,
Ma Hui
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Hello Ma Hui,
I'm using the TWR-K60F120M. The MCU that is in the board is the "PK60FN1M0VLQ12".
For schematic reference, SCH-27167 rev C.
Best Regards,
Rafael Werneck
Hi Rafael,
I had done a same test with TWR-K60F120M board (SCH-27167 rev C1) and below is the test hardware platform:
I don't modify any hardware design and during the test, the ADC conversion result is stable.
Please check my test result video record.
I am using [FLASH-1M] target and program the TWR-K60F120M board with debugger tool connection.
Have a great day,
Ma Hui
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Hi Ma Hui,
In the SCH-27167, what the difference between rev C and rev C1?
Did you make the reset by the SW3 button? If so, could you try to make the reset by debugger software?
Best Regards,
Rafael Werneck
Hi Rafael,
The difference between Rev C vs. Rev C1 is Rev C1 just replace two obsolete resistors (R13 and R14) with new resistor part number, which does not affect Potention-meter circuit.
In the video, I am using SW3 to reset the board.
I try to use debugger to reset the board, there without any change about ADC conversion result value.
Have a great day,
Ma Hui
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Note: If this post answers your question, please click the Correct Answer button. Thank you!
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