I thought the debugging in AVR Visual studio 7 was significantly worse than in 4 (but I haven't used either very much). Embitz is not officially supported by ST, but generally seems to work very well - apart from the current Windows 10 problem (which isn't exclusive to Embitz). This is best discussed on the microcontroller forum though..
I startet using 8 bit Atmels with the AVR dragon and Atmel Studio 6 (or was it already 7?) two years ago. Since I'm not a professional I don't know what professional developers require. For me, it is just magical seeing the bits changing in the registers while running my program on the chip.
It is a little bit off topic, but Embitz says that my GDL server is not running.
Not necessarily, but there obviously is a limit to how much gain is beneficial.
Hmm. That doesn't look right. What is the output with no load applied? 45mV? ![Huh? ???](https://www.eevblog.com/forum/Smileys/default/huh.gif)
Ah, I get the point. With no load appliead I read 0.4mV and with full load 2mV. I use hacked houshold scales.
Ok. So what is used to generate the 2.5V reference?
What is the filtered 2.5V out of U10B used for?
It's the negative input of one chanel. The 2.5V at the INA122's REF pin give me 2.5V at the positive input when no load is applyed (ideally). This allows me to measure "both ways" forces pushing and pulling on the scales .
What are you exciting the bridge with?
The excitation comes from a LM1117-5.0
Well its not ideal, but it it probably isn't a signifcant source of noise in your circuit. Still it's worth asking the question as to what are you using to create the 5V reference?
The 5V reference voltage is created using a REF195
http://www.analog.com/media/en/technical-documentation/data-sheets/REF19xSeries.pdf, same with the 2.5V reference. Both references are filtered with a circuit smilar shown in the schematics of the 1248 EVM board
https://media.digikey.com/pdf/Data%20Sheets/Texas%20Instruments%20PDFs/ADS1148,1248EVM(-PDK)_Gde.pdf (D1-D2). The op amp in the filter is a LMC6482.
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back on topic
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I appreciate your comments and it seems, that I really messed things up. But I want to go on with this project. What about that front end? It is derived from the OPA388 datasheet
http://www.ti.com/lit/ds/symlink/opa388.pdf. My thoughts on the circuit:
-TI uses it as an example for strain gauge measurement - it might work (besides it is a discrete INA122 )
-I added the suggested input filtering (using X2Y caps saves space and improves performance).
-I added a 1st order RC filter for the ADC
-OPA388 is a zero drift amp (chopper?) giving me probably more stable results
-I could use the OPA2388 minimizing the needed space.
-Instead using the 5025 I could use a voltage divider (VCC to Gnd) feeding the negative input of the ADC too, making the measurement truly ratiometric
-I could connect sense+ directly to REFP of the ADC
Or just using the INA133