Tuesday, March 27, 2012


I have a new favorite microcontroller: the LPC2368. It programs similar to the LPC2148 but is much more "digital" and much less "analog". It has four UARTs, three SPI ports, three I2C ports, something called I2S, two CAN ports (maybe I can talk to my car, or more like listen to it), two USBs, an ethernet port(!) and so on and so on. One big deal is a hardware SD/MMC port. My previous new love was the 2468, but that one has 208 pins and probably wouldn't fit on the Logomatic footprint, much less the stick IMUinator.

This guy has exactly 100 pins. The one big feature that the 2368 lacks is an external memory interface. That and a lot more GPIO pins. For two main reasons, the 2368 is more convenient to work with than the 2148:
  1. More pins means less overlap between functions. Several of the peripherals have dedicated pins (Ethernet, one I2C) so there is no problem with overlap. PWM and UART still overlap, but there are enough pins and two choices for each overlap that you can use all 6 PWMs and all of the UARTS.
  2. Fewer analog inputs, so those don't take as many pins.
The last is the only place where a 2148 is superior. The '2368 has six A/D inputs, but I use one of them for battery voltage, one for current, one for reference, and one is covered up by the USB Vbus input, leaving only two for use. You can sacrifice the voltage reference to get another channel, and I should think about doing the same for battery level and current sensing. It may also be possible to use another plain GPIO pin as Vbus, freeing up another A/D.

All the sensors I plan on using now and in the future are digital anyway, so to me, losing A/D is no big loss.

Also, all the peripherals except I2C have DMA, which I think means you can hand them a big block of data (or tell them to listen for a big block of data) and then the peripheral will take care of itself, while the core continues its programs. No more busy waits for the SD card.

I am working on a Loginator2368 which is increasingly less pin-compatible with the Loginator, but still roughly the same shape and size. Who knows if it can be made to fit on a Stick IMUinator?

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