mosi voltage level

[carlesricart]

Hi,

I'm working with frdm k20D50M. I'm using the Spi, and my MOSI line has the 3.3V max level, and  2.4V low level.

I would like to work with a 0v low level. How do this? with and external translator? there are another possibility?

Thanks

[xiangjun_rong]

Hi,Carles,

As David said that  It is strange that the MOSI pin can not pull to LOW logic, pls check if the pin is connected to a diode, your phenomenon seems that the pin is connected to a diode or the pin is damaged.

The SPIx_OUT(MOSI)  is a push-pull pin if you clear the  ODE bit in corresponding PORTx_PCRn register, even if you set the pin in open drain mode, it means that the High logic can not reach if you do not enable pull-up resistor.

Hope it can help you.

BR

XiangJun Rong

[carlesricart]

Hi,

Something happens with the port, I changed to another one and it works. I take the port directly from the connector in either case.

It's weird becouse the frdm is new!

thanks you both!

[davidsherman · Accepted solution]

Is your device damaged, or is something pulling it up?  Unless you have an unusually strong pull up, it should be close to zero on a logic low and no translation is necessary.  Make sure also that the pin muxing has that pin configured as MOSI, not a digital input.  Are you seeing serial data being sent on that line?