SLAZ681O September   2015  – August 2021 MSP430FR5994

 

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6.4 ADC69

ADC Module

Category

Functional

Function

ADC stops operating if ADC clock source is changed from SMCLK to another source while SMCLKOFF = 1.

Description

When SMCLK is used as the clock source for the ADC (ADC12CTL1.ADC12SSELx = 11) and CSCTL4.SMCLKOFF = 1, the ADC will stop operating if the ADC clock source is changed by user software (e.g. in the ISR) from SMCLK to a different clock source. This issue appears only for the ADC12CTL1.ADC12DIVx settings /3/5/7. The hang state can be recovered by PUC/POR/BOR/Power cycle.

Workaround

1. Set CSCTL4.SMCLKOFF = 0 before switch ADC clock source.

OR

2. Only use ADC12CTL1.ADC12DIVx as /1, /2, /4, /6, /8