di0ib
/
keybrd
Watch 1
Star 0
Fork 0
Code Releases 7 Activity
Browse Source

change tutorial 5 names

tags/v0.6.0
wolfv6 7 years ago
parent
f24ea7aa76
commit
a241d78b94
6 changed files with 67 additions and 25 deletions
Split View Show Diff Stats
  1. BIN
      tutorials/breadboard_keyboard_supplies.ods
  2. 0
    0
      tutorials/keybrd_5a_LED_on_uC/LEDs_back.JPG
  3. 0
    0
      tutorials/keybrd_5a_LED_on_uC/keybrd_5a_LED_on_uC.ino
  4. 2
    3
      tutorials/keybrd_5b_LED_on_IOE/keybrd_5b_LED_on_IOE.ino
  5. 35
    22
      tutorials/tutorial_5a_LED_on_uC.md
  6. 30
    0
      tutorials/tutorial_5b_LED_on_IOE.md

BIN
tutorials/breadboard_keyboard_supplies.ods View File


tutorials/keybrd_5_LEDs/LEDs_back.JPG → tutorials/keybrd_5a_LED_on_uC/LEDs_back.JPG View File


tutorials/keybrd_5_LEDs/keybrd_5_LEDs.ino → tutorials/keybrd_5a_LED_on_uC/keybrd_5a_LED_on_uC.ino View File


+ 2
- 3
tutorials/keybrd_5b_LED_on_IOE/keybrd_5b_LED_on_IOE.ino View File

@@ -49,7 +49,7 @@ PortMCP23S17 portWrite(port_B, 0);
Scanner_IOE scanner_R(LOW, portWrite, portRead);

// ================ RIGHT LEDs =================
//LED_IOE LED_CapsLck(portRead, 1<<6); //tested LED on port A (read)
LED_IOE LED_CapsLck(portRead, 1<<6); //tested LED on port A (read)
//LED_IOE LED_CapsLck(portWrite, 1<<6);//tested LED on port B (write)

// =================== CODES ===================
@@ -62,8 +62,7 @@ Code_Sc s_1(KEY_1);
Code_Sc s_2(KEY_2);
Code_Sc s_3(KEY_3);

Code_Sc o_capsLock(KEY_4);
//Code_LEDLock o_capsLock(KEY_CAPS_LOCK, LED_CapsLck);
Code_LEDLock o_capsLock(KEY_CAPS_LOCK, LED_CapsLck);

// =================== ROWS ====================
// ---------------- LEFT ROWS ------------------

tutorials/tutorial_5_LEDs.md → tutorials/tutorial_5a_LED_on_uC.md View File

@@ -1,5 +1,5 @@
Tutorial 5 - indicator LEDs
===========================
Tutorial 5a - indicator LEDs
============================
Keyboards often have LEDs to indicate CapsLock, NumLock, and other states.
It's one of the first things we look at when a keyboard produces unexpected results.

@@ -9,44 +9,49 @@ The breadboard keyboard modifies the basic breadboard keyboard described in [tut

Add components to the breadboard as shown in the picture.

The three clear plastic cylinders are LEDs.
LED anodes (the longer lead) are powered by 4.7k Ohm current limiting resistors connected to pins 16, 17, and 21.
LED cathodes (the shorter lead) are grounded by a common terminal strip.
The three clear plastic cylinders are red and yellow LEDs.
Each LED is in series with a 4.7k Ohm current limiting resistor.
LED anodes (the longer lead) are powered by pins 16, 17, and 21.
LED cathodes (the shorter lead) are connected to a grounded terminal strip.

!["LEDs"](keybrd_5_LEDs/LEDs_back.JPG "LEDs")

keybrd sketch for driving LEDs
------------------------------
[keybrd_5_LEDs.ino](keybrd_5_LEDs/keybrd_5_LEDs.ino) is a simple sketch with three LEDs.
The sketch will run on the above breadboard keyboard.
keybrd sketch with LEDs
-----------------------
The [keybrd_5a_LED_on_uC.ino](keybrd_5a_LED_on_uC/keybrd_5a_LED_on_uC.ino) sketch will run on the above breadboard keyboard.
As usual, the sketch annotations explain the code.

LED forward voltage
-------------------
Forward voltage is the voltage used by the LED.
Forward voltage is published in the LED's datasheet.

Most blue and green LEDs have about 3.3 forward voltage, which does not reliably illuminate on Teensy LC's 3.3 volts.
Most red and yellow LEDs have around 2.2 forward voltage.
So use red and yellow LEDs on Teensy LC.
Low-current LEDs can go as low as 1.6 forward voltage.

LED brightness
--------------
An LED's current limiting resistor value effects the brightness of the LED.
Lets see how much visual difference resistance makes.
Replace an LED's 4.7k Ohm resistor with a 270 Ohm resistor.
The amount of current (I) going through an LED is directly proportional to how bright it appears.
By picking the correct resistor, you have full control over how bright the LED appears.

It doesn't matter which end of the LED the resistor is on, the important thing is that the resistor and LED are in series.
Lets see how much visual difference resistance makes.
Replace an LED's 4.7k Ohm resistor with a 68 Ohm resistor.

Less resistance makes the LED brighter.
Too little resistance will burn out the LED.
Connecting an LED directly to power will destroy the LED in a bright flash (do not look directly at the LED if you try this).

2-mA LEDs are bright enough for keyboard indicator lights.
Or you can use more resistance on a 20-mA LED to make it dimmer.
The current supplied to an LED should always be limited by a resistor or some other device.

LED current limiting resistor values
------------------------------------
Never connect an LED directly from ground to power. Doing so would destroy the LED.

This formula calculates the minimum resistance for maximum LED brightness:
```
output-pin Supply Voltage Vs
LED Forward Voltage Vf
Forward Current If

minimum current limiting restiance R = (Vs - Vf) / If
From Ohm's Law, minimum current limiting restiance R = (Vs - Vf) / If
```

For Forward Current, use the smaller of:
@@ -59,15 +64,24 @@ Teensy LC output-pin capacities are:
* Teensy LC on-board LED is on pin 13.
It has a current-limiting resistor on the board, and does not provide enough power for another LED.

Voltages and current capacities are published in datasheets and sometimes pinout diagrams.
For Teensy LC 20 mA pin and the TT Electronics OVLLx8C7 LED:
```
output-pin Supply Voltage Vs = 3.3 volts
LED Forward Voltage Vf = 2.2 volts

use the smaller of:
max pin Current If = 20 mA
max LED Current If = 20 mA
max LED Current If = 30 mA

minimum current limiting restiance R = (Vs - Vf) / If = 55 Ohms
```
Add a safety margin for resistor tolerances (1%, 2%, 5%, 10%), and round up to a standard value.
http://www.rfcafe.com/references/electrical/resistor-values.htm

```
55 Ohms + (55 Ohms * 10%) = 60.5 Ohms < 68 Ohms
```
It is safe to use more resistance.

Calculating the resistance for the Teensy LC 5 mA pin is left as an exercise.
@@ -88,7 +102,6 @@ From your LED's datasheet, find:
* Continuous Forward Current (mA)

Calculate the minimum resistance needed for your LED and Supply Voltage.
There are several "LED current limiting resistor calculators" on line.

<br>
<a rel="license" href="https://creativecommons.org/licenses/by/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://licensebuttons.net/l/by/4.0/88x31.png" /></a><br /><span xmlns:dct="http://purl.org/dc/terms/" property="dct:title">keybrd tutorial</span> by <a xmlns:cc="https://creativecommons.org/ns" href="https://github.com/wolfv6/keybrd" property="cc:attributionName" rel="cc:attributionURL">Wolfram Volpi</a> is licensed under a <a rel="license" href="https://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>.<br />Permissions beyond the scope of this license may be available at <a xmlns:cc="https://creativecommons.org/ns" href="https://github.com/wolfv6/keybrd/issues/new" rel="cc:morePermissions">https://github.com/wolfv6/keybrd/issues/new</a>.

+ 30
- 0
tutorials/tutorial_5b_LED_on_IOE.md View File

@@ -0,0 +1,30 @@
Tutorial 5b - indicator LED on IOE
==================================
This tutorial will show you how to add LEDs to an I/O expander.

It is assumed the reader is familiar with LEDs from tutorial_5a_LED_on_uC.md
and familiar with I/O expanders from tutorial_4c_split_keyboard_with_IOE.md.

Adding LEDs to the basic breadboard keyboard
--------------------------------------------
The breadboard keyboard modifies the basic breadboard keyboard described in [tutorial_1_breadboard_keyboard.md](tutorial_1_breadboard_keyboard.md)

Add components to the breadboard as shown in the picture.

The two clear plastic cylinders are red and yellow LEDs.
Each LED is in series with a 4.7k Ohm current limiting resistor.
LED anodes (the longer lead) are powered by pins GPA6 and GPB6.
LED cathodes (the shorter lead) are connected to a grounded terminal strip.

!["LEDs"](keybrd_5_LEDs/LEDs_back.JPG "LEDs")

keybrd sketch with LEDs on IOE
------------------------------
The [keybrd_5b_LED_on_IOE.ino](keybrd_5b_LED_on_IOE/keybrd_5b_LED_on_IOE.ino) sketch will run on the above breadboard keyboard.

The sketch features:
* multiple layers
* split keyboard
* LED on controller
* LED on IOE write port
* LED on IOE read port