Son of Dork: Microprocessor

[dorkus]

The Son of Dork (SOD) project is the result of the diyAudio.com multi-channel preamp initiative (The diyAudio.com preamp project!). The project has been split into threads dedicated to discussion of the preamp's different functional units:

- General Discussion (project status, functional requirements)
- Active Circuitry
- Attenuator
- Power Supply
- Connections and Layout (including input switching)
- Chassis and Construction
- Hardware Logic, Controls, Display
- Microprocessor (programming, implementation)

I will be managing the project as a whole, as well as initially overseeing individual threads. For a background on the project, please see the original thread referenced above. A website dedicated to the project will be located at http://dorkus.org/diy/sod.

Let the fun begin!

[sonnya]

Should we start of choosing a micro!?

If AVR .. At least AT90S8515 but a Mega part would be nice.. Menu's take up a lot of space! .. Even in assembler.

There is even a FreeWare GNU c-compiler avialable..

look at www.avrfreaks.com

Sonny

[dorkus]

i've got a 90S8515 set up at on a dev board at the moment, the part was recommended to me for this application by some folks at avrfreaks.net. but i may step up to an ATMega if necessary... i will be using an external 8k SRAM to store parameters and such but as you say menus may take up a lot of program space in the flash ROM. i'm also not sure if it has enough inputs/outputs for me... i want to have up to 8-channel capability, 8 programmable trigger outputs (for remote amp turn-on etc.), separate memories for each input, etc. etc.... i was doing a rough sketch of my interface specs on the train the other day and it was pretty complicated, i'm going to have a lot of muxing/demuxing to do! i will have to put some more thought into it... when i have a better idea of the control scheme i will post it. i should also get the website for the project up soon...

[sonnya]

Originally posted by dorkus
i've got a 90S8515 set up at on a dev board at the moment, the part was recommended to me for this application by some folks at avrfreaks.net. but i may step up to an ATMega if necessary... i will be using an external 8k SRAM to store parameters and such but as you say menus may take up a lot of program space in the flash ROM. i'm also not sure if it has enough inputs/outputs for me... i want to have up to 8-channel capability, 8 programmable trigger outputs (for remote amp turn-on etc.), separate memories for each input, etc. etc.... i was doing a rough sketch of my interface specs on the train the other day and it was pretty complicated, i'm going to have a lot of muxing/demuxing to do! i will have to put some more thought into it... when i have a better idea of the control scheme i will post it. i should also get the website for the project up soon...

You do not need a lot of pins... Take a look at 74hc165 and 74hc164 .. I use them all the time.

It makes the PCB simpler too.

Sonny

[alvaius]

You may want to consider I2C ports Philips PCA95xx series, Micrel MIC74, etc. for digital control. Some are addressable and being serial, will make layout easier as stated for using simple logic gates. Another nice benefit is that I2C parts need to implement slew control on the edges [for serial transmission] reducing EMI and may lower the chances of digital feedthrough into the analog section which during volume control would be nice. Not the cheapest way to do port replication, but possibly a nice elegant way of doing it.

It is likely that more people out there have Microchip develop tools thatn ATMEL AVR parts. Both are relatively easy to work with.

[peranders]

We use both Microchip PIC and Atmel AVR at work. According to my colleague AVR is the salvation (if you have PIC as an alternative). I, myself have done a couple of projects with PIC and I must agree with my pal. PIC sucks when it comes to a little larger programs (more than 1024 instructions). AVR is nice due to in circuit programming (Flash memory), simple programmer. We use 4434 and 8535 with very good results. I must also point out that PIC's works very well also if the program is well done.

My colleague is real good in programming so if you want to get in contact with him send me a message. I haven't asked him if he is interested, maybe.

[dorkus]

hi peranders,

thanks for the info, it correllates with what i've heard about AVR vs. PIC as well... my sense is AVR is ideal for quick and easy application development, PIC is also very good but requires a little more experience/time to get running. i haven't started progamming in earnest yet as i'm concentrating on the analog circuits at the moment, but i'll try to post more specs on the microprocessor design soon.

cheers,
marc

[stadams]

Hey guys,

Has anyone considered the HC11 (8-bit) or HC12 (16-bit) microcontrollers from Motorola? If you have used them before, you know there is plenty of I/O and A/D for the monitoring that has been mentioned previously, SCI & SPI (no I2C), and more processing horsepower.

Just thought I would throw that hat in the ring.

Later,

[dorkus]

i used the HC11 or HC12 (can't remember which) in school for my junior-year project and it was a nice chip. but i think using AVR parts gives us a lot more flexibility, esp. if you go with an ATMega. those babies are sweet. but i dunno, i'll defer to people who are more qualified in the matter.

[peranders]

HC11 has at least one drawback: it consumes rather lot of power. AVR and PIC is very "ström snål" as we say in Sweden. 1-3 mA at full speed and a few µA at sleep or low speed.