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XBee USB Adapter v2 question

userHead azarubkin 2014-04-11 23:04:41 6100 Views19 Replies
Hello everyone,

I'm trying to use Xbee USB Adapter v2 (DFR0174) for my Xbee project. I'm trying to connect Arduino to Xbee using this adapter. Since it can has TTL outputs, I think I can try to connect Arduino's UART to these outputs, and talk to Xbee.
But I need to know the behaviour of Atmega USB converter chip when it's not connected to USB. Won't it interfere in communications between Arduino and Xbee? From what I observe, it does interfere (Tx line is active high).
Is it possible for DFRobot to update the firmware in order to disable the UART of Atmega when there is no USB connection? Or I could try to do it myself if firmware is open source.

That way, Xbee USB Adapter could be used not only as USB <-> Xbee and USB <-> TTL, but also as TTL <-> Xbee.

Thanks!
2014-06-24 18:05:51 What is about exchanging the RX and TX position to realize the xbee<----->TTL mode
The schematic shows that TTL interface is connect to xbee directly, but the pin number is different. TX connects to TX; RX connects to RX, if you exchange two pins, it should realize the communication.
userHeadPic Grey.CC
2014-06-24 18:05:51 What is about exchanging the RX and TX position to realize the xbee<----->TTL mode
The schematic shows that TTL interface is connect to xbee directly, but the pin number is different. TX connects to TX; RX connects to RX, if you exchange two pins, it should realize the communication.
userHeadPic Grey.CC
2014-06-24 07:16:14 You mean directly connect Xbee to APM, without Xbee USB adapter? That is possible, and it should work, but inserting Xbee into socket is so much more comfortable!.. That's why I thought DFRobot could update its adapter with the ability to disable atMega by, say, jumper. Is it somehow possible?.. userHeadPic azarubkin
2014-06-24 07:16:14 You mean directly connect Xbee to APM, without Xbee USB adapter? That is possible, and it should work, but inserting Xbee into socket is so much more comfortable!.. That's why I thought DFRobot could update its adapter with the ability to disable atMega by, say, jumper. Is it somehow possible?.. userHeadPic azarubkin
2014-05-04 19:12:28 wow autopilot,
Hey, what is about a directly connecting. VCC GND RX and TX.
To connect these four pin to the APM directly,i t should be work.
You could have a try, don't forget to decrease the xbee power to 3.3V and two resisters to RX and TX.
userHeadPic Grey.CC
2014-05-04 19:12:28 wow autopilot,
Hey, what is about a directly connecting. VCC GND RX and TX.
To connect these four pin to the APM directly,i t should be work.
You could have a try, don't forget to decrease the xbee power to 3.3V and two resisters to RX and TX.
userHeadPic Grey.CC
2014-04-29 23:22:27 Grey,

That's why I'd like to disable atMega.
APM is ArduPilot Mega, an autopilot board. I need to add wireless telemetry to my APM module. I thought that DFR0174 could be used as TTL <--> Xbee adapter, but apparently it supports only USB <--> Xbee and USB <--> TTL modes.
userHeadPic azarubkin
2014-04-29 23:22:27 Grey,

That's why I'd like to disable atMega.
APM is ArduPilot Mega, an autopilot board. I need to add wireless telemetry to my APM module. I thought that DFR0174 could be used as TTL <--> Xbee adapter, but apparently it supports only USB <--> Xbee and USB <--> TTL modes.
userHeadPic azarubkin
2014-04-29 19:34:12 azarubkin

I don't think xbee could process two data at the same time.
You connect two module to xbee at the same time. it will be a data conflict.
You module APM is a wireless module? Air programming module?
userHeadPic Grey.CC
2014-04-29 19:34:12 azarubkin

I don't think xbee could process two data at the same time.
You connect two module to xbee at the same time. it will be a data conflict.
You module APM is a wireless module? Air programming module?
userHeadPic Grey.CC
2014-04-29 06:11:41 Sorry for answering late, I was on a vacation. I'm attaching a picture.

As you can see, RX of atMega goes to TX of Xbee and vice versa. When I want to send some data to Xbee, I connect TX of my module to RX of Xbee, but then my TX gets jammed by TX of atMega.
userHeadPic azarubkin
2014-04-29 06:11:41 Sorry for answering late, I was on a vacation. I'm attaching a picture.

As you can see, RX of atMega goes to TX of Xbee and vice versa. When I want to send some data to Xbee, I connect TX of my module to RX of Xbee, but then my TX gets jammed by TX of atMega.
userHeadPic azarubkin
2014-04-15 21:12:14 Hello azarubkin,
It is a little strange. I try the same connection. RX(UNO) to RX(adapter); TX(UNO) to TX(adapter).
I write a sample code to let arduino to send some data all the time. I found both Arduino UNO serial port and xbee get the same data.(xbee adapter usb hasn't received)
I didn't add a resister between them...I check schematic again, sorry it is unnecessary.

Could you attach a picture about your hardware connection?
userHeadPic Grey.CC
2014-04-15 21:12:14 Hello azarubkin,
It is a little strange. I try the same connection. RX(UNO) to RX(adapter); TX(UNO) to TX(adapter).
I write a sample code to let arduino to send some data all the time. I found both Arduino UNO serial port and xbee get the same data.(xbee adapter usb hasn't received)
I didn't add a resister between them...I check schematic again, sorry it is unnecessary.

Could you attach a picture about your hardware connection?
userHeadPic Grey.CC
2014-04-15 02:49:10 Hello Grey,

I tried to connect my board to TTL outputs of adapter. The connections are: TX(board) to TX(adapter), RX(board) to RX(adapter).
If I understand the schematics, TX(adapter) is TX(16U2), that is, RX(Xbee). And Rx(adapter) is TX(Xbee).
But it doesn't work. The TX(16U2) is stronger than TX(board) and it drives the line high all the time. Xbee doesn't receive any data. My idea was to put TX(16U2) into floating state, then the communcations with Xbee could proceed. Are you saying it could be achieved without disabling 16u2 chip?
userHeadPic azarubkin
2014-04-15 02:49:10 Hello Grey,

I tried to connect my board to TTL outputs of adapter. The connections are: TX(board) to TX(adapter), RX(board) to RX(adapter).
If I understand the schematics, TX(adapter) is TX(16U2), that is, RX(Xbee). And Rx(adapter) is TX(Xbee).
But it doesn't work. The TX(16U2) is stronger than TX(board) and it drives the line high all the time. Xbee doesn't receive any data. My idea was to put TX(16U2) into floating state, then the communcations with Xbee could proceed. Are you saying it could be achieved without disabling 16u2 chip?
userHeadPic azarubkin
2014-04-15 01:57:29 Hello azarubkin,
It is no need to disable 16u2 chip.
You could check UNO schematic.
RX(16U2) is connect to TX(328P); TX(16U2) is connect to RX(328P)
It means they can't receive the data at the same time.

I haven't tried, but I think your idea is viable. And it needs to add a resister between UNO and adapter.
You could check xbee adapter schematic and xbee shield schematic:
[url=https://www.dfrobot.com/image/data/DFR0174/XBEE%20Adapter%20V2%20SCH.pdf]https://www.dfrobot.com/image/data/DFR0174/XBEE%20Adapter%20V2%20SCH.pdf[/url]
[url=https://www.dfrobot.com/image/data/DFR0015/xbee%20shield%20V1.4%20sch.pdf]https://www.dfrobot.com/image/data/DFR0015/xbee%20shield%20V1.4%20sch.pdf[/url]
Xbee is 3.3v, it won't be too high.
userHeadPic Grey.CC
2014-04-15 01:57:29 Hello azarubkin,
It is no need to disable 16u2 chip.
You could check UNO schematic.
RX(16U2) is connect to TX(328P); TX(16U2) is connect to RX(328P)
It means they can't receive the data at the same time.

I haven't tried, but I think your idea is viable. And it needs to add a resister between UNO and adapter.
You could check xbee adapter schematic and xbee shield schematic:
[url=https://www.dfrobot.com/image/data/DFR0174/XBEE%20Adapter%20V2%20SCH.pdf]https://www.dfrobot.com/image/data/DFR0174/XBEE%20Adapter%20V2%20SCH.pdf[/url]
[url=https://www.dfrobot.com/image/data/DFR0015/xbee%20shield%20V1.4%20sch.pdf]https://www.dfrobot.com/image/data/DFR0015/xbee%20shield%20V1.4%20sch.pdf[/url]
Xbee is 3.3v, it won't be too high.
userHeadPic Grey.CC
2014-04-11 23:04:41 Hello everyone,

I'm trying to use Xbee USB Adapter v2 (DFR0174) for my Xbee project. I'm trying to connect Arduino to Xbee using this adapter. Since it can has TTL outputs, I think I can try to connect Arduino's UART to these outputs, and talk to Xbee.
But I need to know the behaviour of Atmega USB converter chip when it's not connected to USB. Won't it interfere in communications between Arduino and Xbee? From what I observe, it does interfere (Tx line is active high).
Is it possible for DFRobot to update the firmware in order to disable the UART of Atmega when there is no USB connection? Or I could try to do it myself if firmware is open source.

That way, Xbee USB Adapter could be used not only as USB <-> Xbee and USB <-> TTL, but also as TTL <-> Xbee.

Thanks!
userHeadPic azarubkin