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Proto Board Comparison — Parallax Forums

Proto Board Comparison

HumanoidoHumanoido Posts: 5,770
edited 2009-07-31 01:30 in Propeller 1
What is the actual in-use current draw of one Propeller Proto Board USB in milliamps
compared to one Propeller Proto Board?

Comments

  • mctriviamctrivia Posts: 3,772
    edited 2009-07-28 04:23
    propmod-us_ps_sd i mesure at 52mA running on 3AA bateries. running the attached code.

    prety sure most of that is do to the regulator

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  • HumanoidoHumanoido Posts: 5,770
    edited 2009-07-28 14:02
    No, not that board. I'm interested in the current draw in milliamps
    of the official Parallax Propeller Proto Board USB and the official
    Parallax Propeller Proto Board, to see how much extra the usb
    circuits are drawing in actual use.
  • BradCBradC Posts: 2,601
    edited 2009-07-28 14:22
    humanoido said...
    No, not that board. I'm interested in the current draw in milliamps
    of the official Parallax Propeller Proto Board USB and the official
    Parallax Propeller Proto Board, to see how much extra the usb
    circuits are drawing in actual use.

    They're not. The USB part of those boards is powered by the USB port, not the internal regulators.

    I measured my proto board with one cog in a 1 second waitcnt loop at about 26ma, of which about 20ma was consumed by the regulators and power led. The prop seems to use roughly about 4-6ma at 80Mhz with the crystal oscillator on and one cog running.

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  • HumanoidoHumanoido Posts: 5,770
    edited 2009-07-30 04:45
    So running the Propeller circuit without the regulator and LED, using two 1.5 volt AA batteries, would draw around 6ma per cog...
  • BradCBradC Posts: 2,601
    edited 2009-07-30 08:36
    humanoido said...
    So running the Propeller circuit without the regulator and LED, using two 1.5 volt AA batteries, would draw around 6ma per cog...

    No, the propeller and its first cog appears to draw about 6ma here. That includes the hub, oscillator, PLL and all the fruit. I've seen about 1-1.5ma additional per COG here when they are really working hard bug not hitting the hub much. Hub access appears to increase the power draw not inconsiderably.

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  • DroneDrone Posts: 433
    edited 2009-07-30 09:05
    Look at the Propeller datasheet. They discuss at length the power consumption there.
  • Chad GeorgeChad George Posts: 138
    edited 2009-07-30 14:03
    Last year I made a board that had a limited amount of power available to it, so I did some measurements.

    3 cogs - 33.7mA
    4 cogs - 42.3mA
    5 cogs - 50.1mA
    6 cogs - 58.1mA
    7 cogs - 67.2mA
    8 cogs - 77.1mA

    I started with 3 cogs because I felt that was the fewest number of cogs need by my application to do anything useful.

    Maybe I did something wrong with my test because I'm getting way more than what you guys are saying it should be for each cog.
    Originally, I thought my numbers matched the datasheet, so I didn't question them too much. Maybe I'm reading that graph wrong too.
  • LeonLeon Posts: 7,620
    edited 2009-07-30 15:03
    I/O pins should be configured as outputs for minimum power consumption, they shouldn't be left as floating inputs.

    Leon

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  • BradCBradC Posts: 2,601
    edited 2009-07-31 01:30
    Leon said...
    I/O pins should be configured as outputs for minimum power consumption, they shouldn't be left as floating inputs.

    Leon

    I did test this and found absolutely zero difference on my hacked up proto board. On this board 27 of the 32 pins are floating and no matter what I did surrounding them with various forms of EMF, I did not see a variation in the overall current consumption.

    @Chad George, what regulator did you use for your board? The regs on the Parallax Proto boards quiescent current consumption is almost double what the propeller draws in a relatively low power state. I ripped the +5V unit off, added a very low current 3.0v for the prop and switched the 3.3v reg in as required with a couple of mosfets to get the idle current down to about 4.5-5ma. It "idles" at about 6ma now with one cog sitting in a waitcnt loop in spin, and a second cog running an RTC process at 80Mhz (1000HZ waitcnt).

    The theory is that when the system is "idle" the entire propeller / eeprom is supplied 3.0v from the low-power linear regulator. When we need more juice, the propeller starts up an external +5V SMPS which switches the 3.3v regulator in via a couple of 2N7000 mosfets. This seems to work well and prevents the 3.0v TO92 linear regulator from smoking due to excess power dissipation.

    It's ugly and ungainly, but then it was built from junkbox parts and fits neatly on the Proto Board.

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