Thank you for the informative message. You have literally written what I was planning to do in my mind: i.e. sample ADC and write the results to the SD card. You are absolutely right in the ADC latencies in practice. Also, RS232 transfer does become the brick wall as one needs to sample at high rates (such as what I am interested in). Transfer speeds are simply too slow and cannot keep up. I was hoping that the internal SD card storage would be faster than the RS232 and according to what you are saying, according to my calculations, it is about twice as fast.
In the context of typical Waspmote applications even the 1 Hz sampling rate is more than enough. I totlly agree. However, I was trying to find new ways to make use of this wonderfully flexible Waspmote platform in my new projects. Currently, I am experimenting with a concept for a new project where I need a sample rate of about 20 KHz.
In one of my previous posts, (viewtopic.php?f=14&t=7753
) I mentioned my current sampling rate to be at 2 kHz. That works well for most applications. According to the information you provided, the best I can do is to double this figure to 4 kHz, which is an improvement but still it's a long way off my ideal target of 20 kHz. Therefore, I think I will need to scratch my head for a bit longer to come up with a practical alternative :) (I actually have one alternative that may work in mind but I will provide an update if I manage to get it working. I am sure most waspmote fans will be interested in the results !)
In the meantime, doubling the sampling frequency will be worth doing as it will provide a more accurate information on the signal I am trying to capture.
Once again thank you for your prompt and extremely useful response.