Programming an MSP430F2012IPW

[Psii 0]

OK, so I have encountered a problem. The circuit programs just fine and works... as long as the programming wires (two wires) are connected too the device. Once I remove them, the interrupt routine for SPI will not trigger. When I attatch them, it works again. I also noticed that if I turn the LED on, then unplug the SBW cables, the LED light will become weaker. Does this mean the MSP430 does not get enough current?

[roadrunner84 466]

You might have a supply problem. But more likely, you need to connect the 47k resistor from RST to Vcc. Recommended is to connect a 2.2nF capacitor from RST to Vdd and short TEST to Vdd as well.

[Psii 0]

You might have a supply problem. But more likely, you need to connect the 47k resistor from RST to Vcc. Recommended is to connect a 2.2nF capacitor from RST to Vdd and short TEST to Vdd as well.

Hmmm, as far as I can see, there is a 4,7k ohm resistor between RST (4701 SMD) on the PCB. And TEST is not connected to anything. I disconnected TEST and connected it to VCC, still worked. But when I tried to connect REST to 47k, it stopped working

[roadrunner84 466]

The resistor is recommended at 47k, not 4.7k. You connected it from RST to....? Do not connect TEST to Vcc, but rather to Vdd (GND), leaving it unattached may work okay too.

[Psii 0]

Leaving TEST open or connecting it to ground did not change anything. The system still works while RST is connected to the ez430. I then tried to connect a 47k between RST and Vcc, and it stopped working. 2n2 F to ground did no good either. Tried lower resistors without luck. When connecting RST directly to Vcc, the circuit operates but gives the wrong ADC value.

 

There is a 4.7k pullup to Vcc on the PCB, god knows why. I just know I cannot do anything about that, and it is not sufficient for standalone operation. So I guess I have to emulate the exact component configuration on the RST line in the ez430.

[Psii 0]

Oh, the configuration on the TEST line also seems to matter. If it is not connected during a power cycle, the ADC gives the wrong value.

[Psii 0]

Got it working by adding a voltage regulator as a power supply, 100R pullup and 2n2F pulldown on RST, 100R pulldown on TEST.

[Psii 0]

Scratch that, I am at a loss here. The above configuration worked yesterday. I think the device is set up to be able to run in standalone. 

 

I can get it work doing the following: Power the device. Then short RST to ground for a split second, reseting the device. Works everytime. Any suggestion? Is there a register I can set in order to generate the same condition as when grounding and then releasing the RST line?

[roadrunner84 466]

I grow tired of repeating myself to you. For the third time: use a 2.2nF capacitor from ground to rst. This does basically the same as your "short to ground for a split second".

Make sure your power supply is in the specified range and is stable.

[Psii 0]

I am sorry for being such a pain. I did try a 2.2nF numerous of times without success. Your last post made me realize the purpose of the capacitor. Since my pullup resistor deviates from the recommended value, I figured I had to use another capacitor to get the appropriate charge time. I tried lots of different values. What finally made it work was 178 nF, holding the device in a reset state for just the right amount of time. 

 

The device now operates as intended. Thanks for all your help

[roadrunner84 466]

Alright, sorry if I seemed a bit harsh. 178nF seems like an odd value, why not use a 220nF then? The cause of your starting problems is probably that your power source is rising too slowly, causing corrupt execution during the first few microseconds. Glad to hear it's working now.

[Psii 0]

Yeah that seems like the cause. 220nF didn't work either. Used 2x100nF labeled caps with high tolerance in parallel. Measured their total capacitance to 178nF