i have received the error codes: 8E....(it is really a long data)from ST95HF,which means "reception lost without EOF received",i don not know why,are u guys have the same problem.and this error code occurs only when i use NFC function
Hi Ye zhihuang,
Could you give more details on which command you send, what is the total size of your command, which protocol do you use, which tag are you trying to read or write...
Depending on that the answer can be different.
For information if you do not already know it, the ST95HF has a limited buffer of 528-byte depth (VICC and Type B) / 526-byte depth (Type A) in reader mode (described in section 4.3 Support of long frames, cf. DataSheet).
Thank you so much for your reply.There are our command code:（We select 15693 protocol in reader mode,we want to read 15693 tag）
1、00 02 02 02 09
2、02 ff ff
3、00 09 04 68 01 01 D1
4、02 ff ff
5、00 04 03 26 01 00
7、02 ff ff ff
8、00 02 02 00 00
After we send the 00 02 02 00 00,the ST95HF replys a lot of code back,which more than 50 byte.
And there are some interesting phenomenons we had finded in our process:
1、if we use 3.3V for VPS_TX,the ST95HF never replys error code
if we use 5V for VPS_TX,the ST95HF replys error code
You wrote that you want to use the 15693 protocol to read 15693 tag, but your first command selects 14443A protocol.
For 15693 you should send this command:
-> 00 02 02 01 1D (ISO15693, 52Kbps, Wait for SOF, Mod 10%, Single Subcarrier, Append CRC)
Let me know if this is 15693 or 14443A protocol you want to select.
What was the voltage set on the ST95HF board at design (3.3V or 5V)? You cannot change VPS_TX voltage only, you need to adapt your board when moving from 3.3V to 5V (and vice versa). VPS_TX, VPS_Main, Antenna tunning, ....
You can refer to the ST95HF DataSheet to have more details on commands and DC characteristics (if you do not already have it).
Thank you very much for your reply.
We do want to select 15693 protocol to read 15693 tag.At our design,the VPS is used 3.3V for supply voltage,and the VPS_TX is used 5V for supply voltage.But i do not see any suggestions about the VPS 、VPS_TX have to be designed with the same voltage in the ST95HF DataSheet. There is my design schematic diagram below.Looking forward to your more suggestion.
1) If you want to read/write ISO15693 Tags, you first need to select ISO15693 protocol by sending the following command to the ST95HF:
-> 00 02 02 01 1D
2) What I intended to say by "You cannot change VPS_TX voltage only", is not that you must have VPS_TX = VPS_Main. But if you design your board with VPS_Main = X.X Volts and VPS_TX = Y.Y Volts, you cannot change those values without adapting the board (antenna tuning, capacitors, ...).
You can refer to the application note antenna design to help you and there is a calculation tool too for the antenna (These documents are wrote for the CR95HF but are also applicable to the ST95HF).
May I suggest a discussion thread on this subject that will help you as well (here).
Hope it helps.
Hi,Thank you again for your information.It does help me a lot.
I had follow the antenna design guide and used the calculation tool to design the antenna.Is there any problem with VPS_Main = 3.3Volts and VPS_TX = 5 Volts,would it do harm to the ST95HF.
I sent the following command to the ST95HF to select ISO15693 protocol:
-> 00 02 02 01 09(26Kbps WFS MOD100% Single subcarrier CRC appended), is it OK?
Thank you again.Looking forward to your reply.
There is no problem to use ST95HF with VPS_Main = 3.3Volts and VPS_TX = 5 Volts. One thing to be aware is that the signal on RX1 and RX2 (between RX1-GND and RX2-GND) does not exceed 8 Volts. With your 1Kohm resistor, this is very sufficient to attenuate the signal.
Your command to select ISO15693 protocol is OK and the ST95HF should answer:
-> 02 00 00
And after that the ST95Hf is ready to send RF commands.
Unfortunately,there is another problem with our product,the shell of our product is made up of metal material and the antenna was covered partly,as a result,the distance of detecting tag(ISO14443 tag,A&B) is very short,is there any solution to increase the detecting distance?
How about change the shape of the antenna or modify the shell?
I'm sorry my knowledge on hardware side is not good enough to give you the best answer. The only advice that I can give, is that the antenna should be distant from any metal part as this will disrupt the magnetic field. And in consequence limit the distance for communication. One possibility is to add ferrite materials between antenna and metal but this will not be as well as an antenna without metal around and it could be more expensive.
I let someone more expert help you on this.
I tried to increase VPS_TX from 3.3 to 5V on EVAL-ST95HF like on a picture
I tucked 5 from USB. Also I recalculated capacitors with apps you recommended, and still I do not have any better results.
The idea is to increase reading distance with increasing voltage.
So because I am using eval board can you help me maybe I did something wrong.
Values I got, Ca stays on 82pF, and C22 and C25 are 22pF, and with that values I have same reading distance i have with 3.3V.
Did any one succeeded to increase reading distance and transmitter power?
Hello,For sure by adding magnetic material as metal plane under the antenna you will modify/ reduce the field and potentially will short the communication channel.Did you find ferrite material to introduce between the metal area and the antenna?Otherwise you will have to cut the metal area in order to not disrupt the magnetic field.Regards
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