smclk output

Alexandr Kurkin

Prodigy 110 points

Other Parts Discussed in Thread: MSP430G2553, MSP430F2416

I have msp430g2553 and i trying get SMCLK output on P1.4 pin(ms430 launchpad). This is my settings

    P1REN |= BIT4;
   ADC10AE0 = 0;
   CAPD = 0;
   P1SEL |= BIT4;
   P1SEL2 &= (~BIT4);
   P1DIR |= BIT4;

But I don`t see SMCLK on P1.4.

I have tried to delete pullup for TEST bit, but I hade same result.

over 10 years ago

0 Gunay Turan over 10 years ago

Intellectual 595 points

Hi,

It seems there is nothing wrong with your port settings. But you must provide us with your SMCLK setting code too. Did you configure it?

You can check this document out. Chapter 5 shows how to source SMCLK from DCO or XT2. http://www.ti.com/lit/ug/slau144j/slau144j.pdf

0 Alexandr Kurkin over 10 years ago in reply to Gunay Turan

Prodigy 110 points

I use default registers settings after reset mc(DCOCLK, 1MHz). There are no any addition settings about SMCLK

I think, that SMCLK work propertly because I used it in TimerA clock for led blinking.

0 Gunay Turan over 10 years ago in reply to Alexandr Kurkin

Intellectual 595 points

Alexandr Kurkin said:

P1DIR |= BIT4;

P1SEL |= BIT4;

Should be enough to get the output. Do you get zero at the scope output?

0 Alexandr Kurkin over 10 years ago in reply to Gunay Turan

Prodigy 110 points

I delete pullup(/P1REN |= BIT4;) and get SMCLK on output. This mean, that I cant use pullup/pulldown for SMCLK output?

0 Gunay Turan over 10 years ago in reply to Alexandr Kurkin

Intellectual 595 points

There is a not on slau 144i:

NOTE: Setting PxREN = 1 When PxSEL = 1
On some I/O ports on the MSP430F261x and MSP430F2416/7/8/9, enabling the
pullup/pulldown resistor (PxREN = 1) while the module function is selected (PxSEL = 1) does
not disable the logic output driver. This combination is not recommended and may result in
unwanted current flow through the internal resistor. See the device-specific data sheet pin
schematics for more information

0 Jens-Michael Gross over 10 years ago in reply to Gunay Turan

Guru 227245 points

On most MSPs, the pullup/pulldown is disabled when the digital port output driver is active. Well, since the outputs are push/pull outputs, there is no sense in having the pullup still active. Best case, it makes no difference, worst case the two fight each other, causing a higher voltage drop than necessary while wasting current.

0 Alexandr Kurkin over 10 years ago in reply to Jens-Michael Gross

Prodigy 110 points

Thanks for answer, I understand

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smclk output