Revision as of 16:46, 2 November 2008

Processor discussion

• • Please use the ARM processor (32bit address space) - it has no Bank switching; ARM has a big linear directly addressable memory. Can get flashed by this open source tool: lpc21isp, yahoo download (after user registration).
    • Look e.g. on the cheap LPC214x quote: "...The LPC214x series is the only ARM7® microcontroller family with full USB 2.0 compliance and USB.org certification..." (LPC2144-LPC2148 has 14 ADC multiplexed channels - two internal ADCs). Chip price: digikey.com: LPC2144 US$ 8.4, LPC2148 US$ 11.2. The ARM architecture is "old" (from 1983), wildly known, used, efficient(high mips/watt) and uses low power (different kind of deep sleep).
    • Test/development/production boards:
      • USB powered through USB-flash port, only mentions 2 ADC-ports: embeddedartists.com: LPC2148 Education Board (two USB ports - one for programming via a ftdi-chip(USB<->serial) - and one directly connected to LPC2148)
      • ARM MP3/AAC Player Quote: "...This is my MP3/AAC player project. The difference to most other players is that decoding is not done on a specialized IC (like VS1001), but directly on the microcontroller. It can play MP3 (all bit rates) and AAC (up to ~256 kbps) from SD card in real time. The project is work in progress..."
      • LPC2148-based Line-tracing Race Car Robot Kit
      • ARM7 LPC2148 mini board, ARM7-Base development board for LPC2148
      • ARM1136JF-S-based: buglabs.net, Some applications, bugcommunity wiki
      • Gumstix
      • AT91SAM7S256 (ARM) based: Lego Mindstorms NXT, NXT Programming Software
      • Alekto; DIN RAIL mountable
      • Atmel AT91SAM7X256 based (also ARM): Controller Board Overview, makingthings.com, sourceforge.net: makingthings
    • Open source support:
      • LPC214x USB stack
    • Links:
      • NXP: LPC2141/42/44/46/48 - Single-chip 16-bit/32-bit microcontrollers
      • ARM7 NXP (formerly a division of Philips) LPC Microcontroller
      • Building Bare-Metal ARM Systems with GNU: Part 1 - Getting Started
      • ARM-Projects
      • Embedded USB - a brief tutorial
      • ALDS

--Glenn 14:25, 2 November 2008 (UTC)

User:Hns

This is what has been thought of: a simple processor that still suppports A/D converters and USB. A good candidate appears to be PIC16C765 Cost is approx. 5 USD.

Using an ARM processor just to convert some samples per second into USB appears to be overkill to me on first though. But the PIC is just one of the options to considered. A drawback appears that the ADC resolution is just 8 bit. This is quite coarse for some sensors. 12 bit would be better...

So what we need:

• single chip
• supports USB and approx. 8 ADC channels without many external components
• low power
• readily available development tools

PIC16C765 is a bad development platform, because it can only be programmed once (OTP). It is also not possible to update to newer enhanced firmware version for the same reason.

There is also:

• pic18f2550 US$ 8.2
• pic18f4550 US$ 8.5

But for almost the same or a little more, you get much more with ARM (e.g. LPC2144, LPC2148).

--Glenn 14:23, 2 November 2008 (UTC)