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41
Electronics / Re: Raspberry Pi B+ and Arduino Bot
« Last post by RussellPiBot on March 24, 2015, 11:03:42 AM »
I guess I did not ask the question correctly because your answer appears to speak to the ability of the Bitscope Micro to handle PWM.  I am sure that the Bitscope can handle PWM for the reason you mentioned. 

However, the question is, can the Pi B+ refresh rate keep pace with rapid changes in PWM signal? That still is not clear to me.

Cheers,


42
Misc / Re: Analyzing the Axon series: Coding, Contruction, and Contraptions
« Last post by mklrobo on March 24, 2015, 10:31:02 AM »
Axon series: What is this thing?
:o Whew! reviewed the datasheet, and, oh my!  :o
Here are some of the features;
Features
• High Performance, Low Power AVR® 8-Bit Microcontroller
• Advanced RISC Architecture
– 135 Powerful Instructions – Most Single Clock Cycle Execution
– 32 x 8 General Purpose Working Registers
– Fully Static Operation
– Up to 16 MIPS Throughput at 16 MHz
– On-Chip 2-cycle Multiplier
• Non-volatile Program and Data Memories
– 64K/128K/256K Bytes of In-System Self-Programmable Flash
Endurance: 10,000 Write/Erase Cycles
– Optional Boot Code Section with Independent Lock Bits
In-System Programming by On-chip Boot Program
True Read-While-Write Operation
– 4K Bytes EEPROM
Endurance: 100,000 Write/Erase Cycles
– 8K Bytes Internal SRAM
– Up to 64K Bytes Optional External Memory Space
– Programming Lock for Software Security
• Peripheral Features
– Two 8-bit Timer/Counters with Separate Prescaler and Compare Mode
– Four 16-bit Timer/Counter with Separate Prescaler, Compare- and Capture Mode
– Real Time Counter with Separate Oscillator
– Four 8-bit PWM Channels
– Six/Twelve PWM Channels with Programmable Resolution from 2 to 16 Bits
(ATmega1281/2561, ATmega640/1280/2560)
– Output Compare Modulator
– 8/16-channel, 10-bit ADC
– Two/Four Programmable Serial USART (ATmega1281/2561,ATmega640/1280/2560)
– Master/Slave SPI Serial Interface
– Byte Oriented 2-wire Serial Interface
– Programmable Watchdog Timer with Separate On-chip Oscillator
– On-chip Analog Comparator
– Interrupt and Wake-up on Pin Change
• I/O and Packages
– 51/86 Programmable I/O Lines (ATmega1281/2561, ATmega640/1280/2560)
– 100-lead (ATmega640/1280/2560)
A lot of features on the chip. Does the endurance feature mean that I can only program it 10,000 times? ???
Anyway, I also reviewed the programs involved with it, and it is all in
C language. Specific sensors commands are encased in header files, in which
you have to have in order to control I/O from the sensor. I downloaded
AVR Studio, and that has the datasheet in the help section, with all the other
products in that MCU line.
I have been spoiled by programming the Parallax propeller, in which I could
immediately start programming, and enjoy the accessories.
In the Axon series, I will have to find the commands allowed in building
the code, along with getting copies of the header files, in order to learn
how they are called. I have found some demo code, which is in C, but have
to find out exactly how they are used, in order to use them in my programs.
Accessing a single pin, seems to be linked to a port, in which is programmed
in bytes.(?) I would like to take advantage of the on-board features of
the chip, but have to find the commands to do so.
WHEN I find the commands, I will write a simple C code to turn on each
I/O pin, in sequence, in order to make sure the pin works. The analog
inputs will have to be treated differently, because they are not regular
I/O ports, but take voltage and convert it to a byte translation.
Whew!   ::)
43
Electronics / Re: Raspberry Pi B+ and Arduino Bot
« Last post by mklrobo on March 24, 2015, 08:18:33 AM »
 :) Hello!
I have a Vellman PC scope, @ 12Mhz bandwidth. Audio frequencies are
easy to capture. The Raspberry PI Micro bitscope has 20 Mhz bandwidth,
so you should be able to get better response than me. I would hazard a guess,
that under 500 Khz, or less that 80 Baud, you should be able to get something.
I have gotten a "flash" of data from my calculator with the Velleman PC scope. (9600 baud)
Simply put, if the PWM is in the aformentioned range you should be able to
get something.
Good Luck!   ;D ;D ;D
44
Electronics / Raspberry Pi B+ and Arduino Bot
« Last post by RussellPiBot on March 24, 2015, 07:41:41 AM »
Project:
Pibot using Pi A+ communicating with a custom (stripped down) Arduino Uno using I2C via MCP23017. Bot mobility will be controlled by Arduino PWM and quadrature Hall Effect feedback to Arduino via serial to parallel output latch 74HC595N.

Question:
Can the micro Bitscope and Raspberry Pi B+ be used to view the various signals being generated within the Bot system? I am particularly concerned that the B+ is not fast enough to capture changes in PWM for proper viewing.

Thank you for any advice you may provide.
45
Electronics / Re: Robot Fingers
« Last post by mklrobo on March 24, 2015, 05:50:51 AM »
 ;D Hello!
There was a person in the forum that started to build a robot hand,
actuated by muscle wires, (nitrinol(?)). Another option,  ;) Consider cables in the hand controlled by one motor, or several. Keep me posted.. ;D ;D
46
Electronics / Robot Fingers
« Last post by RoboEd on March 24, 2015, 04:15:16 AM »
I am attempting to build my first robot and have gone for a roboti arm so that I can learn about motors.  One thing I would like is to have fingers where each section bends at the same rate for realism. Would it be possible for this to be controlled from just one motor where the knuckle would be on the human hand? Or would I need a separate motor at each joint of the finger?  Any help would be very much appreciated!
47
Mechanics and Construction / Re: Robot Construction Log
« Last post by bdeuell on March 23, 2015, 12:42:08 PM »
very interesting about the high efficiency relays, I was not aware of the use of permanent magnets in relays.
thank you for sharing.

On the topic of using older electronics technology and voice recognition I saw this video a few weeks ago on a voice recognition chip (apparently designed with robots in mind) http://www.eevblog.com/2015/02/11/eevblog-713-vcp200-voice-recognition-1980s-style/. Im not sure if you can still find the chip shown or a substitute but you may find it relevant.
48
Mechanics and Construction / Re: Robot Construction Log
« Last post by FIFO on March 23, 2015, 11:13:06 AM »
 
Quote
I'd agree with the comments about K-9. It'd be a cool addition to the project to create an outer case similar to K-9, if you're a fan of the show.
   
    That is a good idea and I will definitely consider doing that, however I would like to get the robot working before I work on the aesthetics.

    I have made some progress on the robot and have been able to etch and solder two of the PCBs for the robot. The first one pictured is a voltage regulator circuit, and the second is a relay board that will allow the processor to interface to the motors.

    The voltage regulator is a LP3852 low dropout linear voltage regulator. With a price of four dollars it is not cheap, however its characteristics made it extremely desirable for use in the robot. One of the features that makes is valuable is the fact that the dropout voltage is only about 250mV when driving a 1.5A load, allowing me to use the 6V batteries I was planing on using in the robot.

    I also learned something new about relays, and unfortunately I learned it the hard way. When selecting relays, I tried to find some that was both cheap and would not require a lot of current to drive. After I found some that seemed adequate, I constructed the PCB and soldered the relays only to find that the relays would not activate. After checking the data sheet for the relays I found that they was described as a high efficiency relays. I did some reading online and found that some high efficiency relays use permanent magnets to make it easier for them to switch and are therefore polarized. I was then able to modify the PCB to fix the polarity issue with the relays.
49
Misc / Re: Analyzing the Axon series: Coding, Contruction, and Contraptions
« Last post by mklrobo on March 23, 2015, 08:16:47 AM »
 :) Great idea, mallster!
Also, any mechanical drawings that need to be done, I plan to
put them in Inventor autodesk software. The tutorials are good
reference; but, as I look into the forum, I do not see many people
sharing code for their robots, in the Axon series.  It will take awhile
to get to the end project, but it will be fun! (have to save up money too!)
Thanks!  ;D ;D ;D
50
Misc / Re: Analyzing the Axon series: Coding, Contruction, and Contraptions
« Last post by mallster on March 23, 2015, 03:08:21 AM »
Hi mklrobo,

Just a suggestion- Maybe Webbot studio would be a good way to document and share your project. As a lot of the heavy lifting is already done.

Look forward to seeing what you can come up with.

Mallster
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