Roomba 530 circles around instead of driving forward

[Sean87]

Hi all,

I have just recently started hacking my roomba model 530. I can send commands to roomba but it does not act according to the commands I am sending, instead it just does random movements.

For example, according to SCI, The following command sequence should make roomba to drive forward:

Code: Select all

128 131 137 0 100 128 0

But in my case, the roomba moves forward for like 20 centimeters and starts circling around itself and some other random movements (I made sure that its in a pretty open space so it shouldn't be the proximity sensors).

Can someone please tell me what could be wrong? Am I sending the wrong commands? Should there be a delay between sending command bytes?

Also I would appriciate to know what are the commands for moving back, right and left.

I have another question, Imagin I have a software with 4 buttons to make roomba gor in 4 directions, do I need to send

Code: Select all

128 131

commands each time user clicks on a direction button? Or this bytes should be sent only once when my custom program starts?

Thanks!

[mfortuna]

Just when it starts.

[Sean87]

Can you please tell me what is the correct byte sequence that should I send to Rommba 5XX so it goes straight forward?!

[mfortuna]

128 130 137 0 200 128 0 will put the roomba in control mode and drive it straight at 200 mm/sec. See the spec here:

http://www.irobot.com/images/consumer/h ... manual.pdf

[Sean87]

Any command that I give, also I used some apps from Robor AppStore, all my roomba does is going into SPOT mode. is there something with the roomba? I tried changing my usb to serial cable but I still get the same responce from my roomba.

Even giving commands to turn on/off LEDs will cause my roomba to go SPOT.

I wonder if you have any ideas for whats going on.

[mfortuna]

Make sure you have the baud rate set to 115200.

Also, if you open a terminal program and put your 530 on its base you should see charging info being displayed every second. This will prove you have a working serial port, and least on the RX side.

[Sean87]

Hi again and thanks for your rplies,

I still have the same problem. I did put the roomba in its base, used 115200 as baud rate, I receive nothing but ERROR and BREAK CONDITION (I am using real term).

Might be stupid, but could it be my connection cable? I am just using a normal USB to SERIAL converter cable, I am not sure if this cable is providing less or more voltage levels than roomba can read/write with.

I did check the cable with multimeter and I guess it's max voltage level while sending is -6.7 volts or something like that.

The conenctions: I conenct cables ground to roomba ground , also I am connecting TX and RX as well (tried to swap them but still same problem).

Can you tell me what are your toughts in this case? Do I need a specialized cable or something?

[vic7767]

Yes, a special cable is needed. One that converts TTL to USB. iRobot sells one on their website.

[mfortuna]

Hopefully you didn't damage the roomba which is expecting 0 to 5V only.

Irobot used to sell a serial to SCI cable but I don't see it on their website. Since you already have a USB to serial cable you could have used a serial to SCI cable if you could find one. They were only $9.99.

[vic7767]

The accessory is still offered on the iRobot website for $20 it's under the Create robot subsection. Here's the URL: http://store.irobot.com/product/index.j ... age=family

[mfortuna]

I was referring to the older DB9 to SCI cable which can be used with a USB to DB9 adapter Sean87 already has. That one was cheaper than the USB to SCI.

[Sean87]

Yes guys you were right...I was so stupid I wass feeding roomba SCI with +-8 volts...But I was lucky....I mad a level shift board on a prototyping board with MAX232 and now the roomba is working through terminal and some apps I found on internet.

But I don't receive anything from roomba...maybe I have desteroyed the TX circuitry of roomba? but its RX works for sure as I can drive it around.

Please have a look at my other question maybe you can answer it:

viewtopic.php?f=1&t=16673

thanks!

[mfortuna]

Best way to check RX data is with a terminal emulator. Put your roomba on a dock or plug the power supply into the jack on the side of the roomba. It should display charging info every second.