# Rx calibration: MCU working too long 114

**URL:** <https://discourse.myriadrf.org/t/rx-calibration-mcu-working-too-long-114/2142>\
**Category:** LimeSDR\
**Created:** [20 December 2017 18:42 UTC](https://discourse.myriadrf.org/t/rx-calibration-mcu-working-too-long-114/2142 "2017-12-20T18:42:20Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![azanetti](https://avatars.discourse-cdn.com/v4/letter/a/8e7dd6/32.png) [@azanetti](https://discourse.myriadrf.org/u/azanetti)\
**Post date:** [20 December 2017 18:42 UTC](https://discourse.myriadrf.org/t/rx-calibration-mcu-working-too-long-114/2142/1 "2017-12-20T18:42:20Z")

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Hello,

I’m having consistent issues with Rx calibration on my LimeSDR v1.4s. It is plugged into a Raspberry Pi3 with the provided Y cable (both connectors plugged into the Pi3), yet power is supplied with an external EEZ H24005 providing 9V and up to 2A.  
If I try to calibrate for 1420 MHz with the following command line:

**LimeUtil --cal --start 1420e6 --stop 1420e6 --chans=ALL --dir=RX 2\>&1 | tee cal\_1420M\_bw30M\_chan\_ALL\_dir\_RX.txt**

I end up with errors / warnings:

Reference clock 30.720 MHz  
LMS7002M cache /home/pi/.limesuite/LMS7002M\_cache\_values.db  
Cal sweep over [1420, 1420, 1] MHz, channels=ALL, dir=RX  
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@  
@@ Calibrating for freq = 1420 MHz  
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

Error calibrating (skipping): MCU working too long 114  
SetFrequency using cache values vco:1, csw:107  
Error calibrating (skipping): MCU working too long 114  
SetFrequency using cache values vco:1, csw:107  
Error calibrating (skipping): MCU working too long 114  
SetFrequency using cache values vco:1, csw:107  
Error calibrating (skipping): MCU working too long 114

Cleanup…

After that, unless I remove XXX I get not more errors because it is using the cached values and the output turns into:

Reference clock 30.720 MHz  
LMS7002M cache /home/pi/.limesuite/LMS7002M\_cache\_values.db  
Cal sweep over [1420, 1420, 1] MHz, channels=ALL, dir=RX  
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@  
@@ Calibrating for freq = 1420 MHz  
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

SetFrequency using cache values vco:1, csw:107  
Rx calibration: using cached values  
SetFrequency using cache values vco:1, csw:107  
Rx calibration: using cached values  
SetFrequency using cache values vco:1, csw:107  
Rx calibration: using cached values  
SetFrequency using cache values vco:1, csw:107  
Rx calibration: using cached values

I also get the exact same error if I try to calibrate with LimeSuiteGui.  
I ran into the same issue when using LMS\_Calibrate() in an application (C code, using LMS API). I’m confused: is the result of the calibration correct even-though it triggers errors ? Can the errors returned by LMS\_Calibrate() by safely ignored ? Should I calibrate for the entire bandwidth and enable cached value into my program ?

Here are the information regarding the version of \*ware:

**LimeUtil --info**  
######################################################

## LimeSuite information summary

######################################################

Version information:  
Library version: v17.12.0-gd352c002  
Build timestamp: 2017-12-19  
Interface version: v2017.12.0  
Binary interface: 17.12-1

System resources:  
Installation root: /usr/local  
User home directory: /home/pi  
App data directory: /home/pi/.local/share/LimeSuite  
Config directory: /home/pi/.limesuite  
Image search paths:  
- /home/pi/.local/share/LimeSuite/images  
- /usr/local/share/LimeSuite/images

Supported connections:

- PCIEXillybus
- STREAM
- uLimeSDR

**LimeUtil --make**  
Make device  
Reference clock 30.720 MHz  
Device name: LimeSDR-USB  
Expansion name: UNSUPPORTED  
Firmware version: 4  
Hardware version: 4  
Protocol version: 1  
Gateware version: 2  
Gateware revision: 12  
Gateware target: LimeSDR-USB  
Serial number: 0x9060b00491f29  
Free connection… OK

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<div class="post-metadata">

**Author:** ![andrewback](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@andrewback](https://discourse.myriadrf.org/u/andrewback)\
**Post date:** [21 December 2017 06:42 UTC](https://discourse.myriadrf.org/t/rx-calibration-mcu-working-too-long-114/2142/2 "2017-12-21T06:42:25Z")

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Tagging @IgnasJ.

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<div class="post-metadata">

**Author:** ![IgnasJ](https://avatars.discourse-cdn.com/v4/letter/i/278dde/32.png) [@IgnasJ](https://discourse.myriadrf.org/u/IgnasJ)\
**Post date:** [21 December 2017 08:49 UTC](https://discourse.myriadrf.org/t/rx-calibration-mcu-working-too-long-114/2142/3 "2017-12-21T08:49:08Z")

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Does this happen on Raspberry Pi only, or also on normal PC? Also, to clarify, is the EEZ H24005 power supply is used to power RaspPI and LimeSDR-USB is then powered from Pi? Or is it plugged directly into LimeSDR-USB?

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**Author:** ![azanetti](https://avatars.discourse-cdn.com/v4/letter/a/8e7dd6/32.png) [@azanetti](https://discourse.myriadrf.org/u/azanetti)\
**Post date:** [21 December 2017 16:09 UTC](https://discourse.myriadrf.org/t/rx-calibration-mcu-working-too-long-114/2142/4 "2017-12-21T16:09:10Z")

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I don’t have currently access to device and did not test it with a normal PC (I will test this at the beginning of 2018, both USB2 and USB3).  
But, just to make it clear:

- the Rasperry Pi3 has its own power supply (5V 1A through the micro-USB port) and has only Ethernet connected (no other USB device)
- the LimeSDR is powered by the EEZ through the jack connecter
- the LimeSDR is cooled by a fan running on another power supply

The LimeSDR is drawing about 500mA at 9V, with little variations depending of what it’s doing, so I consider it is not practical to power it from Raspberry Pi3.

I can test on a Pentium 4 desktop with USB2 and Debian Stretch 9.2, or on a laptop that has one USB3 port. The laptop is x64 and I’m free to install any Linux OS on it: what would be the best option for LimeSDR testing ?

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<div class="post-metadata">

**Author:** ![IgnasJ](https://avatars.discourse-cdn.com/v4/letter/i/278dde/32.png) [@IgnasJ](https://discourse.myriadrf.org/u/IgnasJ)\
**Post date:** [21 December 2017 20:37 UTC](https://discourse.myriadrf.org/t/rx-calibration-mcu-working-too-long-114/2142/5 "2017-12-21T20:37:59Z")

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> [@azanetti](#):
>
> The laptop is x64 and I’m free to install any Linux OS on it: what would be the best option for LimeSDR testing ?

Most testing is done on Ubuntu 16.04 so I think it is the best option.

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<div class="post-metadata">

**Author:** ![andrewback](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@andrewback](https://discourse.myriadrf.org/u/andrewback)\
**Post date:** [22 December 2017 17:28 UTC](https://discourse.myriadrf.org/t/rx-calibration-mcu-working-too-long-114/2142/6 "2017-12-22T17:28:53Z")

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> [@azanetti](#):
>
> the Rasperry Pi3 has its own power supply (5V 1A through the micro-USB port)

This is very possibly too small. I would try using a 2A or greater PSU.