This project grew out of an idea I got when I found a couple of 2057 Giant LED Matrix`s. I thought it would be fun to make faces for robots that could monitor the bot like a piece of test gear that sat right on the bot.

I came up with a few ideas for dot matrix "faces" but it wasn`t just ultra-simple to wire in the matrices. They were designed to be driven row/column with the plus lines tied to column and the cathodes individually running out to pins on the display.

Blah... I put it away for a while. Till the other day when the M2 parts arrived to replace the 18X part I blew up while fiddling around. Hey! These 18M2`s are pretty amazing. You can find a robot project right here on this site, and other information on the 18M2.

My brain blasted when I realized as a consequence of being able to run four 4mHz processes at the same time, you could run one process at 4 X 4 16mHz. And the chip designers through in a treat, the setFreq m32 command. Now I had some speed, so I dragged out the 2057 and my soldering iron and went to work. The result is a dandy little 5X7 display that is crammed in behind the display so you could, if you wanted, stack `em in a message display.

Thus this project was born!

It is cool!
It is Cheap!

What a great project for CwhatIcanDo makers, hackers and circuit benders!

Here`s the way I wired it. I`m including this plus the software just so you can trouble shoot. I recommend you take the other wiring approach so there will be a relationship between the numbers on the picAxe chip (B.0, C.0) and the row numbers.

SOFTWARE LISTING:



``````````````````````````````````````````````````
` Faces for Robots
` Uses picaxe 18M2 to create a face screen for robots
`
` Rel 1.0
` Needs serial interface to program
` Analog Input for data logging/comparison
` Digital Input for pcm control, or ser port for motor ctl
` Extra Output if you choose to chain more displays
` Uses: stopped, forward, turn signals, battery,
` Non-Robot uses: Walking Letters 90 degree rotation,
`
`
`--------------------------------------------------
` PicAxe 18M2
`
` Pinout and Definition of Legs
` By Functional Definition
`=======================================
`(SRI / Out / In) B.0 leg 6 `
`(i2c sda / Touch / ADC / Out / In) B.1 leg 7 `
`(hserin / Touch / ADC / Out / In) B.2 leg 8 `
`(pwm / Touch / ADC / Out / In) B.3 leg 9 `
`(i2c scl / Touch / ADC / Out / In) B.4 leg 10 `
`(hserout / Touch / ADC / Out / In) B.5 leg 11 `
`(pwm / Touch / ADC / Out / In) B.6 leg 12 `
`(Touch / ADC / Out / In) B.7 leg 13
`---------------------------------------
`(Touch / ADC / Out / In) C.0 leg 17 `
`(Touch / ADC / Out / In) C.1 leg 18 `
`(DAC / Touch / ADC / Out / In) C.2 leg 1 `
`(SRQ / Out) Serial Out / C.3 leg 2* `
`(In) / Serial In / C.4 leg 3* `
`(In) old reset is now signal C.5 leg 4
`(Out / In) C.6 leg 15 `
`(Out / In) C.7 leg 16 `
`=======================================
`
`----------````````````````````````````````------------------
` The ideal wiring will hook it up this way: Your
` programming life will get so much easier
`
` B.0 B.1 B.2 B.3 B.4 B.5 B.6 Row 1 through 7
` C.0 C.1 C.2 C.6 C.7 Col 1 through 5

` ------------------------------------------------------------
` Program Wide Symbols


`Kick Butt! set it for extreme speed,
` sure it`ll eat more batteries, but you`re using rechargables!
setfreq m32

`pins
`here i discovered the importance of naming and wiring appropriately
symbol row1 = B.3 `B.1
symbol row2 = B.0 `B.2
symbol row3 = B.2 `B.3
symbol row4 = B.1 `B.4
symbol row5 = B.4 `B.5
symbol row6 = B.6 `B.6
symbol row7 = B.5 `B.7 gives orderly bit alignment

symbol col1 = C.6 `C.0, C.0
symbol col2 = C.1 `C.7, C.2
symbol col3 = C.2 ` , C.6
symbol col4 = C.7 `C.1, C.7
symbol col5 = C.0 `C.6 so much need -- so few bits

symbol serialOut = C.3
symbol serialIn = C.4

` system inputs : C.5 - pulsin/on_off and B.7 - analog/pulsin/on_off
symbol p_button = C.5
symbol anaIn = B.7

symbol delay = 5000 ` just kept having to make it bigger
symbol disp = 10

` get going: set data direction registers for brute force!
let dirsC = %11000111 ` 1 outputs, 0 inputs
let dirsB = %01111111 ` 1 outputs, 0 inputs

` set up initial values for predictable operation
let pinsC = %11000111 ` make all C outputs Low
let pinsB = %01111111 ` turns the lights off :-)

` KEEP THIS TABLE HANDY
` Font making tools
`w1 = %01000000 ` Column 1
`w1 = %00000010 ` Column 2
`w1 = %00000100 ` Column 3
`w1 = %10000000 ` Column 4
`w1 = %00000001 ` Column 5

`w2 = %01110111 ` Row #1
`w2 = %01111110 ` Row #2
`w2 = %01111011 ` Row #3
`w2 = %01111101 ` Row #4
`w2 = %01101111 ` Row #5
`w2 = %00111111 ` Row #6
`w2 = %01011111 ` Row #7
`w2 = %01111111 ` turns the lights off

` For my next act, I will simply OR these babies then blip
` `em a screenful at a time??? Nice experiment.

hello:
for b0 = 1 to 30
gosub H
pause 100
next b0
for b0 = 1 to 30
gosub E
pause 100

next b0
for b0 = 1 to 30
gosub el

pause 100
next b0
`letter space time eater
for b0 = 1 to 30
gosub zero

pause 100
next b0

for b0 = 1 to 30
gosub el

pause 100
next b0
for b0 = 1 to 30
gosub O

pause 100
next b0
`word space
for b0 = 1 to 100
gosub zero

pause 100
next b0

world:
for b0 = 1 to 30
gosub W
pause 100
next b0
for b0 = 1 to 30
gosub O
pause 100
next b0
for b0 = 1 to 30
gosub R
pause 100
next b0
for b0 = 1 to 30
gosub el
pause 100
next b0
for b0 = 1 to 30
gosub dee
pause 100
next b0
`word space
for b0 = 1 to 100
gosub zero

pause 100
next b0


goto hello

H:
let pinsC = %01000000 ` Cols High to enable Rows
let pinsB = %00000000 ` light row
pause disp
gosub zero
let pinsC = %00000010 ` Cols High to enable Rows
let pinsB = %01111101 ` light row
pause disp
gosub zero
let pinsC = %00000100 ` Cols High to enable Rows
let pinsB = %01111101 ` light row
pause disp
gosub zero
let pinsC = %10000000 ` Cols High to enable Rows
let pinsB = %01111101 ` light row
pause disp
gosub zero
let pinsC = %00000001 ` Cols High to enable Rows
let pinsB = %00000000 ` light row
pause disp
gosub zero

return

E:
let pinsC = %01000000 ` Cols High to enable Rows
let pinsB = %00101001 ` light row
pause disp
gosub zero
let pinsC = %00000010 ` Cols High to enable Rows
let pinsB = %01011100 ` light row
pause disp
gosub zero
let pinsC = %00000100 ` Cols High to enable Rows
let pinsB = %01011100 ` light row
pause disp
gosub zero
let pinsC = %10000000 ` Cols High to enable Rows
let pinsB = %01011100 ` light row
pause disp
gosub zero
let pinsC = %00000001 ` Cols High to enable Rows
let pinsB = %00111001 ` light row
pause disp
gosub zero
return

el:
let pinsC = %01000000 ` Cols High to enable Rows
let pinsB = %01111111 ` light row
pause disp
gosub zero
let pinsC = %00000010 ` Cols High to enable Rows
let pinsB = %01111111 ` light row
pause disp
gosub zero
let pinsC = %00000100 ` Cols High to enable Rows
let pinsB = %00000000 ` light row
pause disp
gosub zero
let pinsC = %10000000 ` Cols High to enable Rows
let pinsB = %01011111 ` light row
pause disp
gosub zero
let pinsC = %00000001 ` Cols High to enable Rows
let pinsB = %01011111 ` light row
pause disp
gosub zero
return


O:
let pinsC = %01000000 ` Cols High to enable Rows
let pinsB = %00101001 ` light row
pause disp
gosub zero
let pinsC = %00000010 ` Cols High to enable Rows
let pinsB = %01011110 ` light row
pause disp
gosub zero
let pinsC = %00000100 ` Cols High to enable Rows
let pinsB = %01011110 ` light row
pause disp
gosub zero
let pinsC = %10000000 ` Cols High to enable Rows
let pinsB = %01011110 ` light row
pause disp
gosub zero
let pinsC = %00000001 ` Cols High to enable Rows
let pinsB = %00101001 ` light row
pause disp
gosub zero

return


zero:
let pinsB = %01111111 ` turns the lights off :-)
return




W:
let pinsC = %01000000 ` Cols High to enable Rows
let pinsB = %00000000 ` light row
pause disp
gosub zero
let pinsC = %00000010 ` Cols High to enable Rows
let pinsB = %00111111 ` light row
pause disp
gosub zero
let pinsC = %00000100 ` Cols High to enable Rows
let pinsB = %01101111 ` light row
pause disp
gosub zero
let pinsC = %10000000 ` Cols High to enable Rows
let pinsB = %00111111 ` light row
pause disp
gosub zero
let pinsC = %00000001 ` Cols High to enable Rows
let pinsB = %00000000 ` light row
pause disp
gosub zero

return
R:
let pinsC = %01000000 ` Cols High to enable Rows
let pinsB = %00001001 ` light row
pause disp
gosub zero
let pinsC = %00000010 ` Cols High to enable Rows
let pinsB = %01111011 ` light row
pause disp
gosub zero
let pinsC = %00000100 ` Cols High to enable Rows
let pinsB = %01111110 ` light row
pause disp
gosub zero
let pinsC = %10000000 ` Cols High to enable Rows
let pinsB = %01111110 ` light row
pause disp
gosub zero
let pinsC = %00000001 ` Cols High to enable Rows
let pinsB = %01111011 ` light row
pause disp
gosub zero

return
Dee:
let pinsC = %01000000 ` Cols High to enable Rows
let pinsB = %00101101 ` light row
pause disp
gosub zero
let pinsC = %00000010 ` Cols High to enable Rows
let pinsB = %01011011 ` light row
pause disp
gosub zero
let pinsC = %00000100 ` Cols High to enable Rows
let pinsB = %01011011 ` light row
pause disp
gosub zero
let pinsC = %10000000 ` Cols High to enable Rows
let pinsB = %01011011 ` light row
pause disp
gosub zero
let pinsC = %00000001 ` Cols High to enable Rows
let pinsB = %00100000 ` light row
pause disp
gosub zero

return

It`s pretty simple. You have to keep refreshing this to fool the eye into thinking all the lights are lit at once. Really, all the Row Leds are what light up at any one time. Comment out the SETFREQ command and you can watch it run slowly...

Make the column you want to energize a logic one... on a picAxe you can say high C.0, for example.

While you hold the high state on the column select the rows that should be on.
For "H", you would turn all rows high in col 1, counting left to right:
LOW Row1,Row2,Row3,Row4,Row5,Row6,Row7 or, if you use the suggested schematic:
let pinsB = %00000000

When column 1 shows up, it simply lights up all the LEDs in a row by shorting through a 47 Ohm resistor. Remember you are pulsing the LED`s so you can hit them with more current at once, they are only on for 1/5 the time anyway.

You can imagine with all seven rows Low, and all seven LEDs lit, things will get dimmer in that column. That`s why the setFreq m32 command is in there, everything happens so fast, you hardly notice the flickering (in the video, things are actually running slow at times).

If you still can`t let go of the math, you will still have problems with brighter bars appearing where there is only one or two LED`s in the stream. To fix this, you would need a constant current generator to supply 10ma to only one LED, and jack up the voltage to supply 10ma more each time another LED is called into service.

In the real world there will be limits, and I originally started out here just to make faces, these work great and I simply keep refreshing the face so it looks like all the dots are on all the time to human`s who are watching. For this, the cheap and dirty approach works great...

I`m gonna see if I get a picAxe 20m2 to replace the 18 pin model. Or maybe a 28m2? I like the 20 because it`s very inexpensive. I think I want one of those. And, I think I will drive more matrices either by using the extra pins to enable the other matrices.

I`ll put a voltage divider into the analog input and use the value to choose "how happy" the face really is....