Status update at 6.11.2013

So, the last three weeks have been very programming oriented. I finally got the LED of the uC blinking one week ago and this week I have been trying to establish SPI communication between the MSP430 uC and the ADS1292 Analog front end.
I first tried following the SW package I used for an 8051 based uC in my masters thesis, but that naturally didnt work out so well, since the uC architectures are completely different. Today we approached to problem in a divided way together with Gerardo. We have now put aside the old code and we checked the SPI initialization routine from the MSP430 family guide (chapter 35 USCIBx SPI master mode).
So basically we just toggled one bit (UCWRST) of the UCBxCTL1 register, this resets the SPI communication and leaves the reset pin into low position to enable communication. This sounds farely simple task, but took a while to assure from the datasheets and uC libraries that we use correct registers. We quickly checked the function from the debugger interface register value (Code Composer Studio v5) and it seems to reset correctly and then settle to low. So now we should be able to communicate with the ADS 1292...

7. - 21.10. uC proto assembly in switzerland

After assembling succesfully the prototype testing interface in Finland it was time to start programming the device as well as the ADS analog front end. For this Robert wanted to assemble his own prototype in switzerland to enable programming of the ADS1292 through the uC.

Prototype assembly in switzerland

 Therefore Johannes mailed him couple of his uC and ADS adapter- PCBs and Robert soldered them as well manually to the adapters. The result is in the picture below.

Manually soldered 64-pin VQFN MSP430F5308 uC in the adapter PCB.

ADS adapter PCB soldered but not yet connected.

At the moment the interface is still not running and problems occur to connect the uC. Robert is working on it to get a valid connection to the uC.

3.10 testing the microcontroller

On Thursday morning we met with Gerardo and Sonja in the lab to test if the MSP430 uC mounted on the adapter would function. After updating the firmware of the debugger device and assembling the the specified JTAG configuration, we managed to successfully blink two LEDs with the code we learned previously in the workshop Robert had prepared for us (two LEDs blinking with a loop of 50000 empty calculations). In other words, it seems we have a fully functional microcontroller, adapter and programming tools!

23.-29.9.

In the past week we met with Sonja and Gerardo to test the ADS1292 on the adapter constructed previously. We assembled a test circuit from TI and connected 1.5V-3V to the input (variated by a voltage divider done by resistors and a potentiometer). We measured the output with an oscilloscope, but failed to get any rational output signal and called it a day.

Circuit on the protoboard with power sources of 1.8V and 3V 

The next time we met, we tested the ready circuit for an expected gain of ~15.56 dB(?), but looking at the multiplexer configuration of the ADS, it seemed that the switch config had to be programmed separetely, to be able to get the desired gain. No reasonable output was seen.

Later, I managed to finish the µcontroller adapter. I soldered the MSP430 QFN-package by hand and ended up with a fairly good result. The connections seem good according to multimeter measurements, but further testing will show if the chip overheated. This I doubt, because I soldered each pin heating them for only ~2 seconds. Here are some pictures of the final outcome:

Magnified from the previous image.

Finally we met Robert we had meeting on 16 September we discuss about the progress in the project and saw different circuits made by our group members me and Robert then agreed on the time for the meeting about wireless interface and then we had meeting about wireless interface on 18th September and Robert gave me some tasks now we have to work on the wireless interface part more as it is lagging behind.

2.-8.9. and 9.-15.9.

During the past two weeks we have had two microcontroller workshops prepared by Robert and Gerardo. We have learnt this far the very basics of microcontrollers and seen blinking light demos. 

Johannes soldered ADSs onto the PCBs etched previously. He also took photos of the PCBs with and without the components. Some of the photos are shown below. In addition, Usman created a bluetooth connection between two development boards.

Successful and unsuccessful PCBs:

                                          Photo: Johannes Pirhonen

                                          Photo: Johannes Pirhonen  

                                          Photo: Johannes Pirhonen

                                          Photo: Johannes Pirhonen

                                          Photo: Johannes Pirhonen

                                          Photo: Johannes Pirhonen

The first attempt of soldering the ADS onto the PCB failed. There was too much solder and the component also got overheated in the process.

                                         Photo: Johannes Pirhonen

                                         Photo: Johannes Pirhonen

The second try was the charm!

                                          Photo: Johannes Pirhonen

                                          Photo: Johannes Pirhonen

Week 26.08.- 02.09.

We have advanced to the stage that the first prototype construction is approaching. This week Johannes etched the before designed adapters at the University and he will drill the holes soon. These adapters are used for the ICs to connect them to the prototyping board for easy connectivity.

This week Sonja was busy with other studies, hence we have not advanced more in the power source design but she will send the suggestion list for the rest of the team to revise possible new power source chips after realizing that the voltage level was not sufficient to supply both the Analog front end and the Microcontroller (2,7V to 3,6 V).

Meanwhile Robert and Gerardo have started to prepare the first Microcontroller workshop taking place next wednesday...

Week 4.8.2013 - 10.8.2013

During this week Sonja/Johannes/Gerardo designed the PCB design of the power source, the layout design is shown in figure 1. Johannes designed the PCB for mounting the MCU and AFE. Gerardo/Robert has been reading/practicing programming the MSP430 which will take an important role in the communication with Bluetooth device.

Week 4 - 01.07.- 08.07.2013

This week we have worked on the design of the Analog Front End (ADS1292). The sensed signals are adequated using a passive low pass filter (150Hz) and a Voltage-limiting devices (zener diodes). The supply configuration for the ADS1292 consider an unipolar supply configuration.
The model was created using PSPICE 16.4

Week 4 - 01.07.- 08.07.2013

This week we have done (Gerardo continues)...

Week 1- 10.-17.06.2013

Last week we met with Gerardo and Defne, to discuss the inputs and outputs of the circuit and getting familiar with the layout and block diagram. We were unsure about the multiplexer and the analog front end and decided to look more into the theoretical background of the system before further action.

On Monday we had a little meeting with Gerardo, Usman, Robert and myself. We decided to keep on working on the theoretical background. We discussed a bit about the amplifier configurations and Gerardo proposed to meet on Wednesday to discuss further about the I/O.

You guys please comment, if there are key points that i missed.

-Johannes

Official Project Blog

The ECG Sensor Student Project has officially started in Finland on Saturday 01.06.2013 with 7 product developers.