bmp085 with uext connection with BBB

Hello,
I am using bmp085 sensor with uext connection with beaglebone black. I have made change in device tree of BBB. I have made i2c1(pin 17 and 18) as input pin and pulled up internally and set it to mode two. I have also set compatible property in device tree to load module of bmp085.
After looking into hardware design manual of bmp085 I interface with beaglebone black.I connected four wire (vdd(pin3),gnd(pin1),sda(pin17) and scl(pin18)) and kept other unconnected.

https://www.olimex.com/Products/Modules/Sensors/MOD-BMP085/resources/MOD-BMP085_sch.pdf

When I boot my kernel my bmp085 module is loaded automatically and I am getting entry in /dev of i2c1

Problem:
When I connect BBB with bmp085 my kernel hangs or BBB does not start at all!!!What may be the problem???
Note:
I am not using 5v supply.

Can you try connect with external 5V supply ?
BTW, suggest R2 and R3 connect with 10k resister ,

bmp085 sensor works on 3.3v volt. I have internally pulled up the pin and I can see resistor connected in the harware diagram of bmp085.
Still I connect external resistor?

bmp085 sensor works on 3.3v volt. I have internally pulled up the pin and I can see resistor connected in the harware diagram of bmp085.
Still I connect external resistor?

The internal resistors don’t provide enough current. You will still need external resistors and I suggest 4k7.

Regards,
John

I belive that they may not provide required current. But would it cause by BBB not to power on?

I will connect external resistor with sda1 and scl1 pins of BBB which are already pulled up. Where should I connect the other leg of these resistor.

Regard
Jay Kothari

I belive that they may not provide required current. But would it cause by BBB not to power on?

I will connect external resistor with sda1 and scl1 pins of BBB which are already pulled up. Where should I connect the other leg of these resistor.

VDD_3V3B

I belive that they may not provide required current. But would it cause by BBB not to power on?

The pull up resistors will have nothing to do with BBB power up. My bet is you have something connected to LCD_DATA[15…0] which changes the startup mode of the BBB. Anything connected to these pins must be isolated until after the SYS_RESETn goes high. Use a high impedance buffer to isolate these signals and gate then with SYS_RESETn.

Regards,
John

Thank you for such explanation.

But I havnt attached anything on LCD_DATA.

I have four connection.
1)GND(pin1)
2)Vcc(pin 3)
3)SCL(pin 17)-I have pulled up internally
4)SDA(pin 18)-I have pulled up internally

and my BBB is not powering on!!!

As per your suggession how I use pull up resister for scl and sda pin, which I have pulled up internally (from device tree).

Regards
Jay Kothari

I would like to stop this topic by correcting my mistake.

I reversed my connection of uext cable.Afterwards I checked connectivity. Please check the connection when you interface with uext. Thank you for discussion

Regards

Jay Kothari