MSP430FR5969: TIDM-1WIREEEPROM Software with MSP-EXP430FR5969 not working with Maxim DS9490R USB 1-wire adaptor

Hi Mark,

Can you link the previous forum you are referring to or potentially rephrase your issue?

Is the whole system not working? or what specific issue are you seeing?

Regards,

Luke

Luke, 

Thanks for your reply.  The link to the original question is at the top of this post.  

MSP430FR5969: TIDM-1WIREEEPROM Software with MSP-EXP430FR5969 and Maxim DS9490R not Working

I am trying to use the Maxim DS9490R USB adaptor as the 1 wire master to communicate with the MSP-EXP430FR5969 as an emmulated 1 wire eeprom slave device.  The problem is the MSP-EXP430FR5969 is not detected on the 1 wire bus.  From what I can tell it never responds to the search command sent by the master. 

Hi Mark,

I've been looking into this and using this document Memory Emulation Using 1-Wire Communication Protocol as reference and looking through the code. I see you stated that your DS9490R was having a long delay time.

Can you check to see the signal pulses are at the correct lengths as well? The TIDM-1WIREEEPROM-FR5969.c file says it will reset with a 460-600 us long pulse and after 30 us will reply with a 100us long pulse. You might be able to lengthen the values of the pulses in the code to compensate for these increased delays (Effects Not Tested).

Also, the document used a 1 kΩ pull-up resistor, and a 22 µF tank capacitor. Section 4.2 in that document will be important Design Restrictions including what adjusting the resistor and capacitor values will do.

Regards,

Luke

Luke,

The DS9490R is the standard tool we use to read/write to our existing 1-wire device.  The signal pulse timing all looks good.  The only difference I noticed from the app note examples, was the longer time before the search command is sent after the presence pulse is received. 

The 1k pull-up and capacitor is needed for the parasitic mode, but to keep thinks simple I'm currently setup for dedicated power operation.

When connecting to another controller as the master I could see MSP430 dev board responding (after a small timing change to the code).  Here we've set the family code to 0x43.

However, when I add a second slave device to the bus, it no longer responds to the search request correctly. The data sent back for the family and the ROM value are invalid.  The DS9490R also has a slave device (DS1990A ) on the 1-wire bus by default.  I'm wondering if this example code was only intended to be used with 1 master and 1 slave on the bus?  

Thanks for looking into this!

Mark

Hi Mark,

The 1 wire protocol supports bus operation and the code example should also support it. There are hardware differences between the example and your system, this is could be the cause of the long delay between presence and search. The timings could be changed to reflect the hardware differences as well, like you did with the SendBit() function for the other controller. The example code sets the clock speed to 16 MHz so when adjusting the timing that will need to be taken into account.

You are correct, with the dedicated power you only need to connect the data line to the master and pull it up with a resistor, no capacitor needed.

If the MSP430 board works with another controller on a 1 master 1 slave setup can you try using that same controller with a 1 master 2 slave setup? The issue might be with the DS9490R and the DS1990A.

Regards,

Luke

Luke,

I don't think the issue is with the DS9490R.  This is a standard 1wire to USB adapter from Maxim.  We use this adapter and OneWireViewer.exe to read/write all of our 1-wire devices.  We're trying to see if the MSP430 can be used as a drop in replacement for our 1 wire eeprom.  For this to work, we'll need to be able to read/write to it with the DS9490R.  

I did try a second slave device on the bus before, and I couldn't get good comms with MPS430.  I plan on retesting this tomorrow, and I'll let you know what I find.

Thanks,

Mark