Propeller Simple Spin Board Update

PROPELLER SIMPLE SPIN BOARD UPDATE
This update includes the new v1.2 version schematic for the Propeller Simple Spin Board.

Those of you building the BOE disable circuit can now follow the added schematic detail to activate the disabling.

This schematic replaces v1.1 in the following post:
Brain Cortex Update Part 6
and here
http://humanoidolabs.blogspot.tw/2013/07/propeller-simple-spin-board-part-2.html

The additional crisscross wiring improves chip reliability. The BOE disable circuit also requires the 220 ohm resistor from VDD to RESn.

Propeller Simple Spin Board Part 1
Propeller Simple Spin Board Part 2
Propeller Simple Spin Board Part 3
Propeller Simple Spin Board Part 4 & 5
Bare Bones Propeller
Propeller Spin Brain Part 1
Propeller Spin Brain Part 2
Supertronic Spin Brain
Cherry Pie Tiny Super Computer Wannabe
How Slow Can You Go? Processing Speed

Propeller Simple Spin Board Part 6

PROPELLER SIMPLE SPIN BOARD - PART 6

LOOP SWITCH
MAKE a loop switch (see photo) from a curved insulated wire, to switch from BOE ON to BOE OFF. With the BOE Brown Out Enable switch off, low power experiments can be conducted. With BOE ON, when the voltage supply approaches 2.7 volts, a Propeller reset will occur.

SIMPLE LED ON PROGRAM
As promised this is a more simple program to activate the LED on pin 15. With only four code lines, it will turn on the LED and keep in on. Add this simple 4-step program to your code repository for future experiments.

PUB LedOn          ' Method declaration
    dira[15] := 1  ' Set P16 to output
    outa[15] := 1  ' Set P16 high
 repeat            ' Keep LED on

Propeller Mini Project Index

PROPELLER MINI PROJECT INDEX

Propeller Simple Spin Board Part 1
Propeller Simple Spin Board Part 2
Propeller Simple Spin Board Part 3
Propeller Simple Spin Board Part 4 & 5

Bare Bones Propeller

Propeller Spin Brain Part 1
Propeller Spin Brain Part 2

Supertronic Spin Brain

Cherry Pie Tiny Super Computer Wannabe
How Slow Can You Go? Processing Speed

Propeller Simple Spin Board Part 4 & 5

Experiment 4: crisscross wiring

PART 4 & 5 - IMPROVING RELIABILITY
PROPELLER SIMPLE SPIN BOARD
The Propeller Simple Spin Board will be expanded more in the future. Let's make some preliminary preparations for this and improve its reliability. While in it's RC speed state with RCFAST and RCSLOW, the circuit is already reliable and durable.

Experiment 5: decoupling

 









However, at higher clock speed, overclocking, with unusual loads or demands, electrical pressures and imbalances occur internally inside the chip, which is also effected with various operational configs. These conditions are not always for the better. However, it's possible to improve the operation of these circuits with external wiring and components.

Although it's a lot of technical mumble jumble jargon to describe it, basically the Propeller needs decoupling capacitors on each side of the dip chip, as close as possible to Propeller pins VSS and VDD, and a special added "criss-cross" wiring. Propeller experts say both the connective wiring and the capacitors (use a .1 uf value) belong to the chip and help to prevent blowing out the PLL circuits inside the chip.

The wiring connects one side of the chip to the other side. Ground VSS on one side (use a green or black wire) is connected to ground VSS on the other side, and power VDD (use a red wire) on one side is connected to power VDD on the other side. Use shortest wires that run directly over the top of the chip. This circuit will balance the chip's internal circuitry and help prevent a condition that could damage the chip. With these improvements installed, the Propeller chip is ready to run extremely fast and do much more than we ever expected. Stay tuned for more.

Another possible requirement involves using the addition of 10uf and 100uf capacitors for when the Propeller is expanded with additional demands. Due to limitations of breadboard pins nearest the chip, these capacitors may or may not connect at the power rails position.

Propeller Simple Spin Board Part 3

The main battery supply is switched off, however the LED blinker program continues to operated from USB power. The added breadboard circuit controls the brightness of the LED.

PROPELLER SIMPLE SPIN BOARD
Experiment 3 - Running on USB Trickle Power

Last time we disabled BOE (Brown Out Enable) so that our simple prop board could run on low power. We then asked the question, "How low can we go?" Exploring and experimenting led to a discovery.

First we ran the LED blinker program. Then we shut off the 3.0 volts battery power supply expecting the program to shut down and the LED to go off. However, in a darkened room, the LED was dimly continuing to blink, and the program stayed in memory continuing to run properly.

TEST PROGRAM
pub main
dira[15] :=1
repeat
 !outa[15]
  waitcnt(clkfreq*2 + cnt)

The program is modified to slow down the LED blinker so the meter can settle to get a good reading of voltage drop across the LED.

RESULTS
Run the program with the power supply connected. Remove the power supply. With the USB port connected, the prop chip has a 2.32 voltage high from P15 when the circuit's power supply is off and the USB cable remained connected.

Tests were performed on an iMac with an unpowered four port HUB. When the power supply is on, the prop chip has a 3.0 volt high from P15. The simple way to increase the LED brightness is to use a 5 volt LED or a high intensity LED, carefully controlled without the dropping resistor. When switching back to the full 3.0 volts power supply, the resistor must be reconnected beforehand.

A transistor circuit can also boost the power to the LED. The illustration shows an experiment. The shown circuit is found in Parallax' book, "What's a Microcontroller."

CAVEATS
When the main power is shut off, the program continues to run and the LED continues to blink. When the USB is disconnected, there is no power to the prop circuit and the program is lost. With USB power attached again, without the mains power supply, the prop is not detected and the program will not reload.

IDEAS
One idea is to place the amplifier circuit in between the battery power supply and the prop circuit to see if the programs will continue to load on USB power only. The most simple approach - substitute a 5V LED and the LED dropping resistor can be removed to increase the LED brightness. When switching back to the full 3.0 volts power supply, the resistor must first be reconnected. Or simply route the USB +5 Volt line to become the prop's power supply.

LINKS TO PROPELLER SIMPLE SPIN BOARD EXPERIMENTS

Experiment One - Bare Bones Circuit
http://humanoidolabs.blogspot.tw/2013/07/propeller-simplex-spinner.html
http://humanoidolabs.blogspot.tw/2013/07/bare-bones-propeller.html

Experiment Two - Disabling BOE for Low Power Operations
http://humanoidolabs.blogspot.tw/2013/07/propeller-simple-spin-board-part-2.html

Experiment Three - Running on USB trickle power
http://humanoidolabs.blogspot.tw/2013/07/propeller-simple-spin-board-part-3.html

Experiment Four & Five -  Improving Reliability
http://humanoidolabs.blogspot.tw/2013/07/propeller-simple-spin-board-part-5.html

Propeller Simple Spin Board Part 2

Schematic: Simple Spin Board

A LOW POWER PROPELLER
SIMPLE SPIN BOARD

PART 2: Updated schematic, more simple software, 1st circuit to run at low power

 

If you missed Part 1 of the Propeller Simple Spin Board, find it at this link:
Propeller Simple Spin Board

A More Simple Program
Here's a program with 5 statements instead of 7 to blink the LED on pin 15. Later we will show a program with only 4 steps in Spin.
 

FIRST MOD DISABLING THE BROWNOUT DETECTOR

In this first modification to the Propeller Simple Spin Board, the connection from BOEn to Ground is removed. Insert a new connection between BOEn and Vdd. This will disable the brownout detector by connecting it to high, and prevent the board from resetting at 2.7 volts or less. (not shown on schematic)


I can't seem to disable brown out detection, if I connect BOEn to Vdd even at 3.3v the Prop won't do anything.
 
Put an external pullup on RST (a 220 ohm resistor from RST to VDD).

When BOE Brown Out Enable is grounded, the Propeller chip has an internal pullup activated. When BOE is held high, the internal pullup is not active, and an external pullup is required on RST to restore functioning.
VOLTAGES

The Propeller Simple Spin Board is capable of operations at voltages much lower than 3.3, 3.0 or 2.7 volts and disabling the brownout detector BOEn will make this possible. This will allow longer battery operations as the voltage drops down, and running on tiny pen cells, watch batteries and other low power sources. How low can you go below 2.7 volts? This is left as a student exercise. A new schematic will reflect this change. For more information http://tymkrs.tumblr.com/post/116554...pins-explained

Q&A Section

Q - I can't seem to disable brown out detection, if I connect BOEn to Vdd even at 3.3v the Prop won't do anything.

A - Put an external 220 ohm resistor pullup from RST to VDD. When BOE Brown Out Enable is grounded, the Propeller chip has an internal pullup activated. When BOE is held high, the internal pullup is not active, and an external pullup is required on RST to restore functioning.

Propeller Simple Spin Board

Propeller Simple Spin Board

THE MOST SIMPLE PROPELLER BOARD
PROPELLER
SIMPLE SPIN BOARD   PART 1
Perhaps the most simple design for a complete Propeller microntroller computer, the Propeller Simple Spin Board can be used to quickly write and test Spin programs.

Simple Spin Board Wiring

ASSEMBLY
Assembles in 5 minutes using a solderless breadboard. This circuit is more simple than what's shown in the Parallax Propeller Education Kit. Parts include a Propeller chip and label, LED and hookup wire, two decoupling capacitors, and a couple AA batteries in a holder. 

NO THIS AND NO THAT
The program is fed into the chip's RAM so no EEPROM is needed. The 5V LED runs on 3 volts and no dropping resistor is required. Software runs under RC Fast and RC enhancements so no crystal is needed. Batteries are used so no power supply components are needed.

THE BOARD
Stuff is mounted on one third of a Parallax breadboard from a Propeller Education Kit. Wiring is followed using the photo, no schematic needed.

EXTRAS
Extras include red and green colored stick pins for measuring at various points throughout the circuit. The simple battery holder has a lever action on/off switch.

TEST PROGRAM
No project is complete without a test program. This simple Spin program will flash the LED on pin 15.

pub main
dira[15] :=1
repeat
 outa[15] :=1
  waitcnt(clkfreq/2 + cnt)
  outa[15] := 0
  waitcnt(clkfreq/2 + cnt)

PARTS LIST
01 - Propeller Chip P8x32a-d40
01 - Propeller Chip Printed Label
01 - Parallax Prop Plug
01 - 4 Pin Connector
01 - 5V Red LED
02 - .1 uf Decoupling Capacitor
02 - Stick Pin (Red & Green)
01 - Set of Jumper Wires 
01 - Battery Holder with Switch
02 - AA Battery
1/3 Breadboard

PROPELLER PARTS FROM PARALLAX
http://www.parallax.com/PropellerEducationKit/tabid/377/Default.aspx



PROJECT NOW APPEARING AT PARALLAX
http://forums.parallax.com/showthread.php/149069-Propeller-Simple-Spin-Board

OTHER PROPELLER PROJECTS

• Propeller LED Machine
• Propeller Spin Brain Part 2
• Propeller 2
• Supertronic Spin Brain
• Spin Brain
• Fake Supercomputer
• Cherry Pie Tiny Super Computer Wannabe