PeterP

Member Since: March 29, 2007

Country: United States

  • Product DEV-11098 | about 2 years ago

    I’ve been playing with one of these for a couple days and found some quirks. I’ve been using the Teensy for awhile so most of this is in comparison. This is using Arduino 1.0 with the SparkFun Pro Micro Driver. The board is identified as Leonardo.

    There is no easy way to enter the bootloader. You have to connect the VCC to the adjacent RST pin. This connection needs to be maintained the entire time the bootloader is operational. If you disconnect the pin, the device immediately disconnects from the host. This is very annoying if board is not on a breadboard and doubly so if you already have a wire soldered to the VCC hole. I’m going to have to wire in a switch or something.

    The Teensy has a an on-board momentary switch that you press to enter the bootloader. There is no requirement that the switch remain pressed the entire time.

    I also attempted to convert my board to 3.3V operation by clearing the jumper next to the micro USB port. No luck. The voltage regulator doesn’t turn on and no power can be detected past the regulator.

  • Product PRT-00726 | about 3 years ago

    The MAX1555 gets very hot when charging a 700mah single cell li-ion battery through the barrel connector off a 6V unregulated power supply (6.7V nominal). I have smoked two MAX1555s in this manner.
    Powering the board off the USB input solves the problem. I’m now charging off a 5V regulated USB supply. It takes a bit longer to fully charge, but at least I don’t have to worry about it bursting into flames.

  • Product ROB-09571 | about 4 years ago

    Maybe I’m missing something but those current sensing resistors appear to be a bit undersized. At a continuous 2A drive the power dissipated by each pair of 1 ohm resistors is (2A ^2) * 0.5 ohms = 2W. Each resistor should be rated for at least 1 watt.
    I think the sensing resistors are above the Atmega and they appear to be 0603 packages. AFAIK, 0603’s tend to dissipate between 0.1W to 0.25W.
    Assuming a 0.25W resistor the maximum current drive is sqrt(0.25W / 0.5 ohms) = continuous 0.71A max per channel. Or about a 35% duty cycle at 2A.

  • Product PRT-00731 | about 7 years ago

    These batteries are small, but not nearly as light as mentioned in the description. They are actually about 3g each.

No public wish lists :(