How to get a 5V output with STR750 EVAL

[xaviooo]

Posted on May 08, 2007 at 08:34

How to get a 5V output with STR750 EVAL

[xaviooo]

Posted on April 27, 2007 at 10:07

I'm using STR750 Eval board and the example : STR75xStdLib/example/GPIO.

Of course I changed this (instead of 3V3) :

/* GPIO pins optimized for 5V operation */

MRCC_IOVoltageRangeConfig(MRCC_IOVoltageRange_5V);

Then :

/* P2.19 and P2.18 in Push Pull mode */

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_18 | GPIO_Pin_19;

GPIO_Init(GPIO2, &GPIO_InitStructure);

GPIO_Write(GPIO2, 0x00);

-----------------------------------------

I get a 3.3V output on 2.19 (CN7).

-----------------------------------------

What's wrong ? Is there a mask to change ?

I'm using a power supply jack (5V).

JP1 : PSU and DTB fitted.

JP3 : CPU_3V3 fitted.

JP4, JP5, JP6 : not fitted.

Thank you in advance.

[mohamed23]

Posted on April 27, 2007 at 13:14

Hello Xavio,

I think that you have made a misunderstanding about 5Volts subject.

STR75x from ST is 5 Volts tolerant this does not mean that It will output

5volts but it Handles 5 Volts inputs and the output is always 3.3Volts.

If you are interesting to have 5 Volts output, you can use the STR73x series from ST which I found the only ones within the ARM7 micros in market able to drive directly 5volts outputs.

I hope this may help you and make things more clear :-]

bR,

Rave

[javidaboo]

Posted on April 28, 2007 at 05:21

STR750 can operation as either a 5 volt or 3.3 volt device, the I/O output will be at the supply voltage level minus a diode drop.

The only difference on the schematic between 3.3 (Scheme 1) and 5.0 (Scheme 3) is providing 5 instead of 3.3 volts.

I choice to use the 735 device when I started (before the 750 was available) so I can't help you without looking into the library.

Could you please post the answer when you discover the problem.

Barry

[xaviooo]

Posted on April 28, 2007 at 12:55

Well, i'm still confused... especially when I look at this scheme 3 :

Xavio

[ This message was edited by: Xavio on 28-04-2007 16:44 ]

[xaviooo]

Posted on May 02, 2007 at 05:23

Well, I can't find a solution.

Barry, are you sure that it's possible to get a 5V output with the STR750 Eval ?

Rave said that it's not possible...

I'm still trying, I don't want to design another board :p

-Xavier

[javida14]

Posted on May 07, 2007 at 20:37

I went to a semimar when they were presenting the device and that what they indicated. The USB could not be used at 5 volts. That was the only difference. Can I say with 100%, NO, but everything that I read indicates, YES.

I choose to go with the 735 part, because KEIL at that time has simulation for all the on-chip peripherals for the 73x and not the 75x family, and I needed the additional I/O at 5 volts.

Have you tried contacting ST Tech Support. They are suppose to be moniting this site, but its looks like there not.

Barry

[mohamed23]

Posted on May 08, 2007 at 08:34

Hi all,

Well, I haven't seen that the STR75x can operate in Dual Supply with (scheme3).

Here attached the confirmation that you can have a minimum I/O output at (VDDIO- 0.8) from STR75x Datasheet : So , Yes it is possible.

However, if you have the STR750-EVAL from STMicroelectronics, It seems that the scheme3 is not implemented and you have to rework the board or to design your own board with Scheme3 model to have 5 Volts Outputs.

BR,

Rave

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