Re: Development Issue on LPC55S69

Vince Wu (吳家瑋) <Vince.Wu@...>

Hi Lawrence,


Sorry for unclear description.

What I mean is the voltage of MOSI signal in idle state doesn’t remain in high voltage.

For example, the following picture shows it begin from high voltage but end with low voltage.

However, I think the correct behavior is that MOSI should go back to high voltage after data transmission is finished.


Is this normal?



Best regards,



From: Lawrence King [mailto:lawrence.king@...]
Sent: Monday, March 30, 2020 9:30 PM
To: Vince Wu (
吳家瑋) <Vince.Wu@...>; devel@...
Cc: Kevin Chu (
朱國偉) <Kevin.Chu@...>; Clone KL Liao (廖崑霳) <CloneKL.Liao@...>; Wu, Hubert <Hubert.Wu@...>
Subject: RE: [Zephyr-devel] Development Issue on LPC55S69


Hi Vince:


2) I am not sure what you mean when you say “the voltage on the MOSI signal is unstable”. The Oscilloscope traces below look fine, however, the probes on your oscilloscope have not been properly compensated hence you see the ‘tilt’ on the signals instead of nice square waves. Take a look at this article to understand why and how to compensate your probes.


Lawrence King

Principal Developer



From: devel@... <devel@...> On Behalf Of Vince Wu (???)
Sent: Monday, March 30, 2020 12:46 AM
To: devel@...
Cc: Kevin Chu (
朱國偉) <Kevin.Chu@...>; Clone KL Liao (廖崑霳) <CloneKL.Liao@...>; Wu, Hubert <Hubert.Wu@...>
Subject: [Zephyr-devel] Development Issue on LPC55S69




We have some issues on developing LPC55S69 based on Zephyr OS.


1.      EVB can’t run FW successfully if I do operation for double type variable.

I found the FW with this problem will link some more libraries as follows, maybe it cause the problem.


2.      The voltage of MOSI signal for SPI interface in idle state is unstable.

The following 4 situations happen:

  1. Start from high voltage and end with high voltage
  2. Start from high voltage and end with low voltage
  3. Start from low voltage and end with high voltage
  4. Start from low voltage and end with high voltage

For example:


3.      No counter driver.

If I open the counter drivers option in menuconfig, it will build fail.

4.      Bug in GPIO driver, gpio_mcux_lpc.c.

Original source will assign incorrect ISR for the assigned pin.


Please help to answer these problems, thanks.


Best regards,


Vince Wu

Project Lead

Moxa Connectivity Project Development

Fl. 4, No. 135, Lane 235, Baoqiao Rd.

Xindian Dist., New Taipei City, Taiwan, R.O.C.

Tel : +886-2-89191230 ext.1187


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