IMPLEMENTED SO FAR

- Support for 4x20 LCD Display and large number display
- Brightness and contrast adjustment with remote
- (OPUS/Wolfson WM8741) DAC volume control: remote and rotary encoder
- (OPUS/Wolfson WM8741) DAC random filter selection 1 to 5 with remote
- (OPUS/Wolfson WM8741) DAC upsampling selection (L, M, H -this is the OSR setting)
- I2C level shifting (5V to 3.3V)
- Optimized power-up sequence

Saturday, June 20, 2009

New Fonts

Inspired by a new 4-line large font template at the Arduino forums (you can find the link in the sidebar), I decided to tweak my own 3-line Arduino large font.

Basically you create a number of shapes as custom characters and used them to form the large font. However, you are limited by the number of custom fonts you can specify in an LCD (typically 8). The 4-line large font in the Arduino forums is actually the same size as my 3-line large font. But by having 4 lines you have more flexibility in positioning the custom characters "to preety-up" the fonts but you give up some speed in displaying the large numbers (25% speed penalty: 3 lines vs 4 lines).
Here are the results



The left most number displays the selected digital filter in the DAC. Above, I've added an abbreviation to the name of the filter. In this case, LnS is "Linear Phase, Smooth Roll Off".



"LnA" means "Linear Phase, Apodizing". Also displayed is RATE, the input sample rate to the DAC. There is also filter #2: MnS: "Minimum Phase Smooth Roll-off"



"BrK" means "Brickwall" filter. Also displayed is INPT, the input format to the DAC. The WM8141 can receive both PCM (from CD players) and DSD (from SACD players). In the future i will be experimenting with extracting the DSD signal from inside a player and feeding this signal straight to the DAC.



"MnA" is "Minimum Phase, Apodizing" filter. Here RATE has been changed to 48K. Because the incoming signal is processed through a asynchronous reclocker chip to 192KHz, there is a sample rate mismatch and the DAC does not output any sound (In theory, this setting selects the appropriate filters to match the sample rate). In the future I will be using Arduino to control the asynchronous reclocker chip in order to change its output sample rate.

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