28335 ADC External Reference
Altair EmployeeDeal All,
In our board we use Delfino 28335. For ADC we use 2.048V external ADC.
In solidThinking Embedded is it possible to select external reference for ADC?
Answers
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Hi,
Here's a link to the TMS320x2833x Analog-to-Digital Converter Module Technical Reference.
http://www.ti.com/lit/ug/spru812a/spru812a.pdf
Page 43 describes the ADC Reference Select Register. You should be able to create an external write to this register from within your diagram to set bits 15-14 to 01, selecting an external 2.048V reference.
Use the embedded block Extern Definitions as shown in the attached diagram to write to the ADC reference selection register as shown within the Initialize block. It looks like the base address for the ADC is 0x0B00, but you should verify this yourself and change ADC_BASE to the correct ADC base address the ADC_REF_REGISTER definition block.
Define your own ADC_REF_REGISTER:
#define ADC_REF_REGISTER *((volatile unsigned short *)(ADC_BASE+0x1C))
Since bits 13-0 must be preserved, we read-modify-write the value of the register to clear bits 15-14 without changing bits 13-0.
ADC_REF_REGISTER &= 0x3FFF
Then we set the new value (01) of bits 15-14, selecting the external 2.048V reference, into the register with another read-modify-write.
ADC_REF_REGISTER |= 0x4000
After you Tools->Code Gen, it's often interesting to view the generated C code. You should be able to find the C statements generated from the External Definition blocks described above.
The blocks included in the attached diagram must be copied into your existing F28335 diagram which has a Embedded->Delfino->F28x Config Block.
Tom
Corrected attached diagram
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