1. MSP432™ MCUs Training Part 6: Analog Peripherals
ADC14 COMP_E REF
Welcome to part six of the MSP432 MCU Training series. In this section we will cover the analog peripherals including the ADC14, the Comparator E and the Reference Module.

2. + ADC14 | Overview 14-bit Accuracy 32-input channels
INL <= +/- 2 LSB;
DNL <= +/- 1 LSB
ENOB 13-bit
32-input channels
Single-ended & differential Inputs
2 Window comparators
High interrupt
Low interrupt
In [Between] interrupt
Separate internal channels for AVcc and TempSensor
Ultra Low current consumption
Single ended 1.8V, 1Msps
Differential 1.8V, 1Msps
ADC14 Memory Registers
A/D Converter
REF Voltage Select
Sample / Hold
I/P
Multiplexer A1 A2 A4 A3
BATT
TEMP
MOD
Clock
Starting with ADC 14, it is a 1 mega sample 14-bit ADC that provides high performance, high resolution while maintaining low power consumption. In terms of accuracy, the ADC 14 achieves extremely low INL and DNL errors while maintaining extremely high enough at more than 13-bit. While using in differential mode, there are 32 input channels that can be used in either single-ended or differential input modes. The ADC14 also includes 2 window comparators, there are two separate channels that can be used to monitor the supply voltage or AVcc as well as an internal temperature sensor. As mentioned earlier, while providing a high performance, high resolution ADC, this module obtains extremely low power consumption with single ended mode it consumes 210uA at 1.8V and 1Msps while the differential mode consumes 260uA at 1.8V at 1Msps.

3. ... ADC14 | New Features Reference 32-input channels 14-bit ADC Core
Internal
Channel
Mapping
= New Feature
= Enhanced Feature
Reference
external
internal 01
Enhanced Clock
14-bit ADC Core
external
Differential Measurement
internal
32-input channels 01
external
internal 01
The ADC14 is the next revolution of the ADC modules in the MSP Family. Comparing to the ADC12 which is a 12-bit resolution ADC popular on several MSP430 devices, there are many new features that were introduced on the ADC14. First off let’s take a look at the window comparator. ADC14 introduces a 14 bit window comparator and this feature is extremely useful for particular applications that need to monitor an analog signal to check when it falls within or outside a certain range. Traditionally you would have to constantly monitor the signal, perform the sample in conversion and then compare in software to see if it falls within the range or outside the range. Using the window comparator, you could configure the input threshold levels, high and the low thresholds and the ADC14 will continuously convert the result and internally compare the sample result against the threshold. It will trigger the interrupts depending on whether it falls below, between or higher than the window. So this is very useful to keep the device low power, since no CPU activity is required until the analog signal falls within the range of interest.
Enhanced ADC Memory
14-bit Window Comparator
...
Interrupt

4. ADC14 | Window Comparator
Internal
Channel
Mapping 01
32-input channels
14-bit ADC Core
Enhanced ADC Memory
14-bit Window Comparator
Enhanced Clock
Reference
external
internal
Differential Measurement
Interrupt
...
= New Feature
= Enhanced Feature
Set ADC14INIFG
Set ADC14HIIFG
Set ADC14LOIFG
ADC14HI threshold
ADC14LO threshold
Configurable input threshold levels
Conversion results automatically compared against the thresholds
Hi, Lo, and In interrupts indicate which range the result falls in
Same thresholds shared among all channels
Useful for low power because device can stay in sleep mode until result falls in window
In this example below, we have an analog signal that is being monitored and after we have programmed the high and the low threshold of the window comparator depending on whether you want to enable, below, between or above interrupt you can set the flag to trigger the CPU to wake up when the signal falls within the right range. So as you can see at the moment the signal will set the ADC in between flag, as the signal rises above threshold, it could set the high flag, then again the in between flag and the low flag.
14-bit Window Comparator

5. ADC14 | Window Comparator Example
Set ADC14HIIFG
ADC14HI threshold
ADC14LO threshold
Set ADC14INIFG
(The next enhancement that was introduced to ADC14 is the Differential measurement. This feature could be quite handy if you want to monitor two signals and measure the difference between the two signals. Traditionally again, CPU is required to invoke the two measurements and use CPU to compute the difference and determine whether that is of interest. With the Differential Measurement feature you can configure the ADC14 to automatically measure two channels, measure the difference and store that difference directly into the ADC memory register.
Set ADC14LOIFG

6. ADC14 | Differential Measurement
Internal
Channel
Mapping 01
32-input channels
14-bit ADC Core
Enhanced ADC Memory
14-bit Window Comparator
Enhanced Clock
Reference
external
internal
Differential Measurement
Interrupt
...
= New Feature
= Enhanced Feature
VREF+
VREF- A1 A2 ∆
A1 voltage
A2 voltage
Difference
ADC14MEMx Register
Combine input channels to create differential input channels
ADC will measure the difference between two channels and store this value in the ADC14MEMx register
Differential Measurement
Next we have another feature that is new to ADC14 that is Internal Channel Mapping. So traditionally on ADC12 modules there are some dedicated external as well as some dedicated internal channels. Some of the internal channels are temperature sensors as well as ADC monitor channel. So sometimes for certain applications that require absolutely as many input channels as possible it can be inconvenient that some channels are fixed. With this in mind ADC14 introduces the channel mapping capability that gives you the flexibility whether or not to use an internal or external channel

7. ADC14 | Internal Channel Mapping01
32-input channels
14-bit ADC Core
Enhanced ADC Memory
14-bit Window Comparator
Enhanced Clock
Reference
external
internal
Differential Measurement
Interrupt
...
= New Feature
= Enhanced Feature
Internal
Channel
Mapping 01
...
A26-31 can map to either an External Input or Internal ADC input
Internal inputs include the temperature sensor and battery monitor
See the device datasheet to see what internal inputs are available on what channels – varies by device
That way if you want to use an internal temperature sensor you can. Or if you have a better source of higher resolution temperature sensor externally, you can also choose to use the same channel but with external input

8. ADC14 | Other enhancements
Internal
Channel
Mapping 01
32-input channels
14-bit ADC Core
Enhanced ADC Memory
14-bit Window Comparator
Enhanced Clock
Reference
external
internal
Differential Measurement
Interrupt
...
= New Feature
= Enhanced Feature
Some ADC12 implementations have up to 16 channels
More clock sources, including:
MODOSC = 25MHz SYSOSC = 5MHz
32 ADC14MEMx registers
Enhanced Clock
32-input channels
There are some other enhancements that have been introduced to ADC14 for example, now we have up to 32 input channels, this is a big increased compared to some ADC12 implementations with only 16 channels. The clock is also enhanced to set more sources. Since the ADC14 operates at up to 1Msps, it requires a much higher clock. The higher clock source for ADC14 is MODOSC which can run up to 25MHz . However, when ADC14 runs at a lower sample rate such as 200Ksps it does not require higher clock source, a slower clock sources such as SYSOSC running at 5MHz can be used. This allows ADC14 to consume less power and be more efficient.
Enhanced ADC Memory

9. Comp_E | Overview Interrupt driven for low power
Uses the REF module like ADC14
Up to 15 external input channels
Ultra-low-power comparator mode
Software selectable RC filter
Selectable reference voltage generator
Voltage Hysteresis generator
Output internally connected to Timer A capture input (for event capture & capacitive touch implementations)
The next analog module that MSP432 MCU introduces is the Comparator E. This is an ultra-low power comparator that has been introduced in previous MSP Families. The comparator E is created for ultra-low power consumption. It could be interrupt driven for low power operating modes. It has up to 15 external input channels and it also used the reference modules for the reference voltage. The output of the comparator E is also internally connected to the Time A capture input. This way you can create an event capture or use it for capacitive touch implementation. There are two instances of Comparator E provided in the MSP432P4xx Family

10. REF | Reference Module Generates voltage references for analog modules
1.2V, 1.45V, 2.5V
Available on output pin
Scale-able power options
Static mode for high precision outputs
Sampled mode for low-power operations
Two operation modes:
Continuous Mode: reference output continuously on
Burst Mode: reference output on only during ADC conversions
Two buffers to throttle power consumption:
Large buffer for continuous mode or output VREF to pin
Small buffer for burst mode
Provides temp sensor channel for ADC
Option to disable to minimize power
The next analog module that is introduced in the MSP432 family is the reference module. The Reference Module is extremely flexible with different power as well as operating modes that the reference can be used to generate the voltage output for various analog modules. The different voltages are 1.2V, 1.45V and 2.5V. The reference could also be brought out to an external pin that can be used to drive external peripherals. As mentioned, the reference can be programmed in two different power modes. The static mode for high precision as well as sampled mode for low power operations. If the reference is only required for ADC conversion, it can be put in burst mode, where the reference output is only available during the conversions. However, if the reference output is also used to drive an external component it can be put on the continuous mode, to have it continuously on. Depending on the power mode, there are two buffers that can be used to throttle the power consumption. In burst mode where the reference module is only needed at certain times, a smaller buffer can be used. However, for driving an external component, a larger buffer is used. Knowing what your system requires can help you throttle the power consumption for your entire device. Similar to other MSP devices the reference module is also used to drive the power for the temperature sensor. This is the internal temperature sensor channel that the ADC can use to measure the internal temperature of the device. With this we have concluded the analog peripherals chapter of the MSP432 training. We have covered the 1Msps ADC module, the comparator E, as well as the highly flexible reference module on the MSP432. Thanks for watching!