# Inconsistent rsp when following the RPI tutorial
**URL:** https://discuss.blues.com/t/inconsistent-rsp-when-following-the-rpi-tutorial/3048
**Category:** Troubleshooting
**Created:** [May 20, 2025, 6:19pm UTC](https://discuss.blues.com/t/inconsistent-rsp-when-following-the-rpi-tutorial/3048 "2025-05-20T18:19:10Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@smoser](https://discuss.blues.com/u/smoser)
#### Post date: [May 20, 2025, 6:19pm UTC](https://discuss.blues.com/t/inconsistent-rsp-when-following-the-rpi-tutorial/3048/1 "2025-05-20T18:19:10Z")
Hello all,
This is my first delve into the Blues, and very new to programming in general.
I’m following [this tutorial](https://dev.blues.io/guides-and-tutorials/collecting-sensor-data/notecarrier-pi/raspberry-pi/python/), and I’ve made it down to step 7 of “Write Code”. I I have tried changing the port address from 0 to 0x17 per some google searching, without change.
Here is my code:
```auto
# This script is used to test the functionality of a Blues Notecard
import json
import notecard
import notecard_pseudo_sensor
from periphery import I2C
import time
#Taken from bluesnotehub under devices>summary
productUID = "com.xxx.xxx:dev_project"
port = I2C("/dev/i2c-1")
card = notecard.OpenI2C(port, 0x17, 0)
#card = notecard.OpenI2C(port, 0, 0)
#Configure the Notecard:-------------------------
req = {"req": "hub.set"}
req["product"] = productUID
req["mode"] = "continuous"
print(json.dumps(req))
rsp = card.Transaction(req)
print(rsp)
#--------------------------------------------
```
And the response is:
```auto
{"req": "hub.set", "product": "com.xxx.xxx:dev_project", "mode": "continuous"}
{'crc': '0000:A3A6BF43'}
```
Per the tutorial, I should receive an empty {} indicating a successful request.
What does {‘crc’: ‘0000:A3A6BF43’} indicate?
If I continue through the tutorial, I can create mock sensor readings, send them to Notehub rsp={‘total’: 1, ‘crc’: ‘0001:15CB2833’} where they are visible in the Events tab.
Since the tutorial states I should receive an empty JSON object if successful (my rsp is not empty), but the data is sent successfully (also without an empty JSON rsp), am I getting an error or is the documentation outdated?
---
### Author:  [@abucknall](https://discuss.blues.com/u/abucknall)
#### Post date: [May 20, 2025, 8:08pm UTC](https://discuss.blues.com/t/inconsistent-rsp-when-following-the-rpi-tutorial/3048/2 "2025-05-20T20:08:49Z")
Hi @smoser
Welcome to the Blues forums!
You’re on the right track, there are a couple of things you’ve covered that actually need better documentation / updating on our side.
1. Using `card = notecard.OpenI2C(port, 0, 0)` is valid as internally this calls the default I2C address of the Notecard (0x17). Are you unable to use the `OpenI2C()` function with the default parameters?
2. The tutorial was likely written before we introduced the [CRC feature](https://dev.blues.io/notecard/notecard-walkthrough/advanced-notecard-configuration/#validate-notecard-responses). CRCs, as you are seeing, are in fact a sign of a successful request, and we use them to verify the integrity of the transmitted payload. They are enabled by default for requests made from the note-python library. If you’re interested in seeing where this feature comes from in the note-python library, you can find it [here](https://github.com/blues/note-python/blob/c12bcfda788ee9871850270894e28ba02fd178b7/notecard/notecard.py#L230).
Hopefully that helps provide some clarity around what you are seeing.
Thanks,
Alex
---
### Author:  [@smoser](https://discuss.blues.com/u/smoser)
#### Post date: [May 20, 2025, 8:19pm UTC](https://discuss.blues.com/t/inconsistent-rsp-when-following-the-rpi-tutorial/3048/3 "2025-05-20T20:19:10Z")
Thank you Alex for the speedy response. While I don’t know how to use the OpenI2C() function yet, I can send and request information using the Notecard.
Concerning CRC responses, thank you for confirming what I had suspected!