MSP430G2312 won't work standalone

[Pavelas 0]

Hi,

I have small problem, but i didn't start MSP430 uC standalone. On launchpad board everything works perfectly, but now i buld my own PCB, but it's not working.

Everything works fine in debug mode. but if i turn off, and turn on power supply, program doesn't start.

I think problem is /RST pin.

I saw in datasheet, it must be connect to VCC with pullup 47k resistor, and connect to GND with 2.2nF Pulldown capacitor.

My first version was without capasitor, but today i connected capacitor, but still the same problem.

Wachdog is turned off in first code line.

 

What I can try more?

 

Thanks.

[roadrunner84 466]

You could try pulling the TEST line down to GND. (you should indeed connect the /RST as you did)

 

Do you use a crystal, have you installed it on the other board as well?

[Pavelas 0]

You could try pulling the TEST line down to GND. (you should indeed connect the /RST as you did)

 

Do you use a crystal, have you installed it on the other board as well?

I'm using internal oscilator - without external crystal.

 

Ok, will try pulldown TEST line.

 

But yesterday when i meassured voltages on pins (because i thought maybe some problems with voltages) uC starts. Maybe i shorted something. But next time after turn on, the same problem..

[roadrunner84 466]

As the TEST pin has no output driving, your voltage meter's internal resistor is able to pull it down to a defined ground level. You basically use your meter as the resistor or short to ground.

[Pavelas 0]

As the TEST pin has no output driving, your voltage meter's internal resistor is able to pull it down to a defined ground level. You basically use your meter as the resistor or short to ground.

I'm placed also pullup resistor (10k) on TEST. Maybe that's the problem? need leave TEST pin floating?

[roadrunner84 466]

No, you need to pull down the TEST.

[Pavelas 0]

No, you need to pull down the TEST.

with resistor or capacitor (like /RST)?

 

I programmed one board with msp430g2553 uC, where was pullup resistor and pulldown capacitor on /RST pin. TEST pin was open. And everything works perfectly.

[roadrunner84 466]

With a resistor, so to sum it up:

+---\_/---+
| MSP430G |
|         |
|    /RST |---------------+--[47k]--(+)
|         |               |
|    TEST |--[47k]--+    --- C
|         |         |    ---
+---------+         |     |
                   ===   ===

get it? ;-)

 

Leaving TEST open might work just fine, but you may sometimes boot up and get "stuck" in bootloader/SbW/JTAG mode, pull it down for more robust booting behaviour.

[Pavelas 0]

With a resistor, so to sum it up:

+---\_/---+
| MSP430G |
|         |
|    /RST |---------------+--[47k]--(+)
|         |               |
|    TEST |--[47k]--+    --- C
|         |         |    ---
+---------+         |     |
                   ===   ===

get it? ;-)

 

Leaving TEST open might work just fine, but you may sometimes boot up and get "stuck" in bootloader/SbW/JTAG mode, pull it down for more robust booting behaviour.

Now everything is clear. Thanks for help. Tommorow i will try it.

 

Also one question about capacitor: which value is optimal? I'm using 2.2nF, maybe try with 10nF?

[roadrunner84 466]

Using a larger value does not really matter, unless you're programming the MSP with that capacitor connected. When programming, the capacitor should not exceed 2.2nF. The TEST and /RST lines are used by the programmer to load your firmware, with too large a capacitor, the required clockrate cannot be reached.

[Pavelas 0]

Using a larger value does not really matter, unless you're programming the MSP with that capacitor connected. When programming, the capacitor should not exceed 2.2nF. The TEST and /RST lines are used by the programmer to load your firmware, with too large a capacitor, the required clockrate cannot be reached.

ok, thanks. i will try and say it works or not.

[Pavelas 0]

With a resistor, so to sum it up:

+---\_/---+
| MSP430G |
|         |
|    /RST |---------------+--[47k]--(+)
|         |               |
|    TEST |--[47k]--+    --- C
|         |         |    ---
+---------+         |     |
                   ===   ===

get it? ;-)

 

Leaving TEST open might work just fine, but you may sometimes boot up and get "stuck" in bootloader/SbW/JTAG mode, pull it down for more robust booting behaviour.

Now it's working perfectly. Thanks

[RobG 1,892]

You don't need TEST resistor, leave it "floating."

[roadrunner84 466]

TI's datasheets recommend tying it down. As I said, it might work left floating, but rather define it as low by pulling it down to ground.

[tripwire 139]

Just to check, is it OK to leave the 47k pulldown resistor on TEST during programming? I'm hoping the launchpad's emulation board will be still able to drive the TEST pin up as required despite the pulldown. Thanks