Skip to main content
J
Jack_Chen
Visitor II
December 19, 2023
Solved

Problems with using load modulation in transparent mode

  • December 19, 2023
  • 1 reply
  • 3192 views

在目前的项目中，已经实现ST25R3911B作为主机，ST25R3916B作为从机，使用透明模式收发数据。
我希望可以在透明模式中使用负载调制，以实现自定义的协议，我尝试使用ST25R3916B在透明模式中使用负载调制，但是没有成功，现象是将位targ=1之后，ST25R3916B的MISO没有收到主机的任何数据，且没有办法使用MOSI发送任何数据。
请问ST25R3916B如何在透明模式中使用负载调制？位targ需要如何配置？

Here is the machine translation:

In the current project, ST25R3911B has been implemented as the host and ST25R3916B as the slave, using transparent mode to send and receive data.

I hope to use load modulation in transparent mode to achieve custom protocol, I tried to use load modulation in transparent mode with ST25R3916B, but failed, the phenomenon is that the MISO of ST25R3916B did not receive any data from the host after targ=1. And there is no way to send any data using MOSI.

How does the ST25R3916B use load modulation in transparent mode? How do I configure a bit targ?

 

Best regards

 

 

    This topic has been closed for replies.
    Best answer by Ulysses HERNIOSUS

    Hi,

    was never claiming that with targ=0 that you would have something on EXT_LM. Only with targ=1 while doing load modulation on the PICC. 

    Good that it works for you but just again the warning: targ=0 transparent receiver should not give a demodulated signal on MISO but a correlated signal.

    BR, Ulysses

    1 reply

    U
    Ulysses HERNIOSUS
    Technical Moderator
    December 21, 2023

    Hi Jac_Chen,

    did you set SCLK=1 during that operation to enable the receiver?

    Even so I have my doubts if that can work as you imagine: Load modulation as performed by the ST25R3916 will have only small effect on the external reader field. The receiver in card mode on the other hand is built to receive strong AM/OOK reader modulation. It can be that the own load modulation will not trigger the receiver which is active at this point of time.

    Regards, Ulysses

    J
    Jack_ChenAuthor
    Visitor II
    December 21, 2023

    很高兴收到回复！
    我尝试过设置targ=1和SCLK=1，ST25R3916B作为从机仍然无法收到主机的信号，如果targ=0，那么接收是正常的；
    另外，当我控制MOSI不停翻转时候，使用示波器观察主机天线上面的载波信号，载波的幅度没有任何变化，说明ST25R3916B并没有进行负载调制。
    我需要确认ST25R3916B使用负载调制，是否需要设置位targ=1。

    Glad to receive a reply!
    I have tried to set targ=1 and SCLK=1, ST25R3916B as the slave still cannot receive the signal from the host, if targ=0, then the reception is normal;
    In addition, when I controlled the MOSI to keep flipping, I used an oscilloscope to observe the carrier signal on the host antenna, and the amplitude of the carrier did not change, indicating that the ST25R3916B did not carry out load modulation.
    I need to confirm that ST25R3916B uses load modulation and whether it is necessary to set bit targ=1.

     

    Best regards

    U
    Ulysses HERNIOSUS
    Technical Moderator
    December 22, 2023

    Hi Jack_Chen,

     

    targ=1 is required to perform load modulation. Depending on setting of lm_ext and lm_ext_pol I expect also that you will be able to observe its operation on EXT_LM pin.

    I assume you have both ST25R3916B in transparent mode? The host/PCD with targ=0 and the target/PICC with targ=1. Correct? Who is modulating now? At which subcarrier frequency? 

    Can you share logic analyzer traces (combined of host and target) and scope shots?

    BR, Ulysses

    Terms & ConditionsAccessibility statement