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MSP430FR2355: a/d pulse mode using sequence of channels ???

Part Number: MSP430FR2355

I am trying to understand Fig 21.13 of the users guide.  In particular I am using a timer that goes off every half second.  I would like to take a sequence of channel readings (from A4 - A0).  The source for ADCSHS is TB1.1.  I am in pulse mode.  My understanding is that when TB1.1 goes off this will generate SHI (figure 21.7).  This in turn will create a SAMPCON based on time I put into a register.  My questions are:

1.  In 21.13 I am using the rising edge of TB1.1 to go from state Wait for Trigger to state Sample Input Channel X.  The return path for the other channels is MSC and SHP = 1.  My question is how does SAMPCON have a falling edge after the first sample has been taken. when I travel the path (MSC = SHP = 1) given that I do not have another rising edge until a half second later? (falling edge is shown in fig after state Sample Input Channel).

2.  The second question is if SHT is set to 8 clocks and assuming I only need the 1st edge of SHI to trigger all (see above #1) is the math : 1 syn + 5 channels * ( 8 sample + 14 convert + 1) = 116 clocks total to do the 5 channels?

Thanks

  • Hi Steve,

    Thank you for posting to E2E. I will leave a detailed reply by the end of the day, thank you for your patience. 

  • Hi Steve,

    1. MSC and SHP = 1 means that when the timer pulse is detected (SHI rises to 1 to trigger SAMPCON), the MSC (Multiple Sample and Convert) bit will automatically trigger successive conversions. SAMPCON will go low after the first conversion of the sequence occurs, but because MSC = 1, this will not affect the sequence of conversions. So A4 will trigger from SHI rising to 1, and you will follow the MSC and SHP = 1 return path until you reach the end of the sequence (A0). Once completed, you will take the long path back to Wait for Enable, set ADCENC, then use the next TB1.1 pulse to trigger the ADC sequence again. 

    2. This math seems correct - assuming 1 syn means a synchronize clock signal. 

  • Thanks Aaron.....

    It confirms what I thought

    Steve

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