PROJECT
UPDATE
PART 6
SUNDAY OCTOBER 27 2013
IN THIS EDITION!
* BATTERY SIZE
* BATTERY COMPOSITION
* JAR SIZE
* MODULE ARRANGEMENT
* BATTERY CAPACITY CHART
* BOE DECISION
JOIN US AS WE BUILD a real live electric brain cortex. The cortex lives in a tiny home inside a hermetically sealed jar, eating and dining on continuous power, and can talk to the outside world. You can make the cortex your friend and teach it about life. It will learn from you and maybe carry on some your knowledge from generation to generation.
To assure uninterrupted flow of energy to the hungry and continuously dining Cortex, the use of tiny and weak AA batteries was dropped. In place, a series of more massive supply energy capable D size cells are now in use. A single D cell provides 12,000 mAh while the AA cell is only 2,700. The use of four D size cells wired to give 3 volts to the Propeller powered Brain Cortex will supply a full 24,000 mAh.
2) As a result of switching to more massive D size cells, the one liter jar is no longer large enough. The project is examining a 3 liter jar for current use.
3) The use of super capacitors is currently dropped in the overall design due to their unavailability.
4) The arrangement of modules inside the brain is paramount. The solar cells must be at the front. Two sets of large batteries cling to 90 degree opposing sides. The back and bottom are being examined for non-obstructed attachment without battery insertion and removal interference. Switching to jars larger than one liter, such as the three liter jar, has opened up possibilities for other module arrangements.
5) It's noted that other composition batteries cells don't provide the full 1.5 volts and combining two batteries would be insufficient to operate the Propeller chip for the defined term. For this reason, and for the common availability, alkaline batteries were selected.
6) A decision is made to switch
from BOE ON to BOE OFF. With the BOE Brown Out Enable switch off, the cortex will operate on lower
power as the battery has less voltage during the night. With BOE ON, when the voltage supply
approaches 2.7 volts, a Propeller reset will occur. If at all possible, a reset condition is exactly what we want to avoid. For wiring, see the link below.http://humanoidolabs.blogspot.tw/2013/08/propeller-simple-spin-board-part-6.html
http://humanoidolabs.blogspot.tw/2013/07/propeller-simple-spin-board-part-2.html
DISABLE 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.
TYPICAL CAPACITY OF BATTERIES (UNITS IN MAH)
AAA size, 1,200 alkaline, 540 carbon–zinc, 800–1,000 NiMH
AA, 2,700 alkaline, 1,100 carbon–zinc, 3,000 Li–FeS2, 1,700–2900 NiMH, 600–1000 NiCd
C BATTERY, 8,000 alkaline, 3,800 carbon–zinc, 4,500–6,000 NiMH
D BATTERY, 12,000 alkaline, 8,000 carbon–zinc, 2,200–12,000 NiMH
9 VOLT, 565 alkaline, 400 carbon‑zinc, 1,200 lithium, 175–300 NiMH
120 NiCd, 500 lithium polymer rechargeable, 580 mercury, obsolete
Brain Cortex Index Part 16