My mbed no longer functions! Just when I was really getting into it.
Details:
I was doing some work with the ADC and measuring the voltage across a current sensing resistor of a SEPIC converter. The ground wire was removed while the MOSFET was stilll firing. I was working with a 14 to 20 volt input on the converter. It was drawing less than 1 amp. The 3.3 Vout was used as the clamp for the input on the ADC through a diode.
Problem:
There is now a dead short from the 3.3 of IC5 LD1117S33 to GND. All the diodes check out O.K and IC5 was removed and there is still a short. The means that it has to be from one of the other microchips on the board. I'm thinking that it's the LPC1768 but there is no way of telling since there are no diodes from the 3.3V to any of the chips on the board, so there is no way of isolating any of the chips.
Possible solution:
The options are:
1. Apply enough voltage an see which chip gets hot which might also damage other chips that are working.
2. Remove the LPC1768.
3. Get a new mbed board.
If I remove the LPC and it is not the faulty chip, then the chances are the heat from removal may damage the chip. Seeing that I don't have an LPC1768 chip anywhere within an oceans distance, that rules that option out. I'm also the same oceans distance from getting an mbed board.
It was good while it lasted. I must say that it was one of the best development boards I have every used. It made things so easy, datalogging, PWM control and ethernet connectivity and the list goes on. Overall it is a very impressing board and I am very greatfull for the opportunity to use it. I will definetly consider using the mbed LPC1768 in future projects. But for now...it is back to trying to cram code into 8 bit micros and having to worry about all the timing constraints.
Where do all the dead mbed boards go?....mheavean?
Leon Heller.
2
replies
My mbed no longer functions! Just when I was really getting into it.
Details:
I was doing some work with the ADC and measuring the voltage across a current sensing resistor of a SEPIC converter. The ground wire was removed while the MOSFET was stilll firing. I was working with a 14 to 20 volt input on the converter. It was drawing less than 1 amp. The 3.3 Vout was used as the clamp for the input on the ADC through a diode.
Problem:
There is now a dead short from the 3.3 of IC5 LD1117S33 to GND. All the diodes check out O.K and IC5 was removed and there is still a short. The means that it has to be from one of the other microchips on the board. I'm thinking that it's the LPC1768 but there is no way of telling since there are no diodes from the 3.3V to any of the chips on the board, so there is no way of isolating any of the chips.
Possible solution:
The options are:
1. Apply enough voltage an see which chip gets hot which might also damage other chips that are working.
2. Remove the LPC1768.
3. Get a new mbed board.
If I remove the LPC and it is not the faulty chip, then the chances are the heat from removal may damage the chip. Seeing that I don't have an LPC1768 chip anywhere within an oceans distance, that rules that option out. I'm also the same oceans distance from getting an mbed board.
It was good while it lasted. I must say that it was one of the best development boards I have every used. It made things so easy, datalogging, PWM control and ethernet connectivity and the list goes on. Overall it is a very impressing board and I am very greatfull for the opportunity to use it. I will definetly consider using the mbed LPC1768 in future projects. But for now...it is back to trying to cram code into 8 bit micros and having to worry about all the timing constraints.
Where do all the dead mbed boards go?....mheavean?