Analog to Digital Converter (ADC)
Description:
This function will set the configuration of the ADC for one step of a sample sequence. The
ADC can be configured for single-ended or differential operation (the ADC_CTL_D bit selects
differential operation when set), the channel to be sampled can be chosen (the ADC_CTL_CH0
through ADC_CTL_CH23 values), and the internal temperature sensor can be selected (the
ADC_CTL_TS bit). Additionally, this step can be defined as the last in the sequence (the
ADC_CTL_END bit) and it can be configured to cause an interrupt when the step is complete
(the ADC_CTL_IE bit). If the digital comparators are present on the device, this step may also
be configured to send the ADC sample to the selected comparator using ADC_CTL_CMP0
through ADC_CTL_CMP7. The configuration is used by the ADC at the appropriate time when
the trigger for this sequence occurs.
Note:
If the Digitial Comparator is present and enabled using the ADC_CTL_CMP0 through
ADC_CTL_CMP7 selects, the ADC sample will NOT be written into the ADC sequence data
FIFO.
The ui32Step parameter determines the order in which the samples are captured by the ADC when
the trigger occurs. It can range from zero to seven for the first sample sequence, from zero to three
for the second and third sample sequence, and can only be zero for the fourth sample sequence.
Differential mode only works with adjacent channel pairs (for example, 0 and 1). The channel select
must be the number of the channel pair to sample (for example, ADC_CTL_CH0 for 0 and 1, or
ADC_CTL_CH1 for 2 and 3) or undefined results are returned by the ADC. Additionally, if differential
mode is selected when the temperature sensor is being sampled, undefined results are returned
by the ADC.
It is the responsibility of the caller to ensure that a valid configuration is specified; this function does
not check the validity of the specified configuration.
Returns:
None.
5.2.1.25 ROM_ADCSequenceUnderflow
Determines if a sample sequence underflow occurred.
Prototype:
int32_t
ROM_ADCSequenceUnderflow(uint32_t ui32Base,
uint32_t ui32SequenceNum)
ROM Location:
ROM_APITABLE is an array of pointers located at 0x0100.0010.
ROM_ADCTABLE is an array of pointers located at ROM_APITABLE[5].
ROM_ADCSequenceUnderflow is a function pointer located at ROM_ADCTABLE[11].
Parameters:
ui32Base is the base address of the ADC module.
ui32SequenceNum is the sample sequence number.
Description:
This determines if a sample sequence underflow has occurred. This will happen if too many
samples are read from the FIFO.
April 8, 2013 51
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