This is the way it is implemented today, but it may be possible to use the ARM DAC (digital to analog converter) to generate more complex waveforms. I haven’t looked at the DAC capabilities of the DSO Nano processor specifically, but generally this approach is used to synthesize just about any waveform, including replay of pre-recorded samples. Input to the DAC is typically by DMA (Direct memory Access) from either RAM or FLASH.
Ah …, we don’t want that – I’ll provide an update (APP 3.02) to fix this.
The new approach to sampling makes the Nano useful also for a crude view of RS-232/RS-485 and even I2C and SPI at moderate frequencies. The Nano can also supplement a protocol analyzer in that we can see the shape of digital pulses to determine if we have issues with decoupling, floating grounds, transients etc. To make a good digital protocol analyzer however we would need an additional connector for general purpose I/O (e.g. 8 channels).
In the thread on V2.5x I wrote a brief guide on how to use the firmware and you may want to read this.
“No File” suggests that the card is present and we have successfully read the FAT table. Next step is to locate the directory entry and this where it fails. That is, the requested file was not found or some other error occurred. Some early Nano’s had hardware issues with SD cards (search the forum for more input on this) and if this applies to you, further testing may not help. As a general guide however, these are the steps that work for me:
Format the SD card in the DSO Nano with either FAT16 or FAT32 (not NTFS)
Download the file “DSO Files.zip” from the first post in this thread and then extract and copy the files to your card
Select menu option “FI” and sub option “Save Img”
Make sure you select (left/right key) a file that actually exists (e.g. S 0001.BMP)
Press B (or long M) to save
If successful, the info field will advance to “S002.BMP” and you should be able to open and view the screen capture bitmap file on your host computer
I’m using my DSO Nano (first generation) with Windows XP and have tried with FAT16, FAT32 and also a blank OEM formatted card (2GB SanDisk)