Friday, June 1, 2012

STM32F0 Basic Part1

//STM32F0 Reference manual PG 127/742
Turn on/off a Pin (Example Pin C8)

  /* Enable clock for GPIOC                                                   */
  RCC->AHBENR |= (1 << 19);

  GPIOC->MODER  |= (1 << 16);//Set pin C8 as output

  GPIOC->OTYPER &= ~(1 << 8);//Set pin 8 output as internal push-pull

  GPIOC->BSRR |= (1 << 24);//Turn Pin C8 off
  GPIOC->BSRR |= (1 << 8);//Turn  C8 on



Read a pin (Example Pin A0)
RCC->AHBENR  |= (1 << 17);               /* Enable GPIOA clock         */

GPIOA->PUPDR    |=  (1 << 0);         /* PA.0 is  Pull up         */


if((GPIOA->IDR & (1 << 0))==(1 << 0))//read pin state
{
       //High
 }
 else
 {
        //Low
  }

Set up external pin interrupt (Example Pin A0)
 Config pin as input (above)
    EXTI->IMR |= (1 << 0); //unmask External interrupt line 0 (PA0)

    EXTI->RTSR |= (1 << 0); //Enable rising edge trigger of line 0
    EXTI->FTSR    |= (1 << 0); //Enable falling edge trigger of line 0
   
    NVIC_EnableIRQ(EXTI0_1_IRQn);//Enabe EXTI0_1 IRQ


put this segment in the source file
//use extern "C" if the file is .cpp

extern "C" {
    void EXTI0_1_IRQHandler(void)
    {
         //to do
    }
}



Sunday, March 25, 2012

I2C Write, Read sequence

Write
Start, Write_Address, Data_Bytes, Stop

Read
Start, Write_Address, Register_Address, Read_Address, Stop

Thursday, December 1, 2011

FreFilterMessage in a Form VB.NET

under class declaration, implement IMessageFilter

Public Class frmMain
Implements IMessageFilter

add public function PreFilterMessage

_
Public Function PreFilterMessage(ByRef m As System.Windows.Forms.Message) _
As Boolean Implements IMessageFilter.PreFilterMessage
'Filter MouseWheel message
If (m.Msg = 522) Then
Return True
End If
Return False
End Function

in form.Load, add Application.AddMessageFilter(Me)

Friday, June 11, 2010

Nordic FOB and nRF24L01+ Interfacing

Receiver schematic

Datasheet

Characteristics

• 2.4 GHz wireless

• 0-10Mbps 4-wire SPI

• 8 bit command set

Pin functions

      SPI

MISO Digital Output, SPI Slave Data Output, with tri-state option

MOSI Digital Input, SPI Slave Data Input

SCK Digital Input, SPI Clock

CSN Digital Input, SPI Chip Select

     Power

VCC Input Power +3.3v

GND Common Ground

    Other

CE Digital Input, Chip Enable Activates RX or TX mode

IRQ Digital Output, Maskable interrupt pin. Active low

Interfacing

A. Configure nRF24L01+ via SPI

Note: Every command start with a CSN pin on low and end with a CSN pin on high

A command usually has two bytes:

The first byte is the command (read register, write register with register address).
Page 51/70 of the datasheet is the list of commands

Page 57/70 of the datasheet is the register map

Example firmware for AVR controller
If the command is a read command, the second byte is a dummy byte (any value).
If the command if a write command, the second byte is the data to write to the register.


B. Uses

1 Wait for new data by using interrupt. nRF24L01+ will activate a low interrupt when there is new data

2 Set wireless to standby mode by set pin CE to low

3 Activate SPI on nRF24L01+ by set CSN to low

4 Send read command (0x61)

5 Read 4 bytes data to a variable

6 Clear RF FIFO interrupt by send 2 bytes (0x27, 0x40)

7 Disable SPI by set CSN to high

8 Set wireless to monitor mode by set pin CE to high

Data information

Key information is in the first byte of the 4 bytes data.

Used for Nordic FOB

0x17 Left button

0x1E Bottom button

0x1B Right button

0x1D Top button

0x0F Center button

Tuesday, May 4, 2010

Turn off monitor in Windows

You can set up your computer to automatically turn off the monitor after idling for x minutes in power settings.
However, If you want to turn it off right now, what can you do?
-If the monitor has a power switch, just use it.
-Turn off your computer.
-My laptop does not have a power switch, and I want it to be running at night. Here is a simple solution.

Use SendMessage API to send WM_SYSCOMMAND message to HWND_BROADCAST

WM_SYSCOMMAND reference

LPARAM value
-1 - the display is powering on
1 - the display is going to low power
2 - the display is being shut off

#include <windows.h>
int main()
{
   Sleep(3000); // Wait for you to get rid of the mouse.
                //If you move the mouse, the monitor will turn on again.
   SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, (LPARAM) 2);
   return 0;
}

It's time to go to bed.

Friday, April 9, 2010

Simple Keyboard Simulation Using SendInput function

Need to include <windows.h> header file
SendInput
INPUT structure
KEYBDINPUT structure

This function simulate a keyboard press to any active window

1. Create INPUT structure
INPUT *key; //pointer to INPUT structure

key=malloc(sizeof(INPUT));//allocate memory for INPUT structure pointed by key

key->type = INPUT_KEYBOARD;
key->ki.wVK = Virtual_Key_Code; //see Virtual Key Code list for the full key list
key->ki.wScan=0;
key->ki.dwFlags=0;
key->ki.time=0;
key->ki.dwExtraInfo=0;

2. Call SendInput function

SendInput(1,key,sizeof(INPUT));

3. Free memory

free(key);

4. Note
This function works with all active windows. If you need to send a key press to inactive windows (minimized or hidden windows), use SendMessage or PostMessage

PostMessage(hwndWindow, WM_KEYDOWN, Virtual_Key_Code,0);//Press the key down
PostMessage(hwndWindow, WM_KEYUP, Virtual_Key_Code,0);//Release the key

hwndWindow: Handle of the window you want to send a keyboard button to, hwndWindow can be obtained by using FindWindow or FindWindowEx
WM_KEYDOWN: constant = 0x100
WM_KEYUP: constant = 0x101

This method may not work with some applications especially games that use Direct Input.

Virtual Key Code List
VK_LBUTTON (0x01)
Left mouse button

VK_RBUTTON (0x02)
Right mouse button

VK_CANCEL (0x03)
Control-break processing

VK_MBUTTON (0x04)
Middle mouse button (three-button mouse)

VK_XBUTTON1 (0x05)
Windows 2000/XP: X1 mouse button

VK_XBUTTON2 (0x06)
Windows 2000/XP: X2 mouse button

- (0x07)
Undefined

VK_BACK (0x08)
BACKSPACE key

VK_TAB (0x09)
TAB key

- (0x0A-0B)
Reserved

VK_CLEAR (0x0C)
CLEAR key

VK_RETURN (0x0D)
ENTER key

- (0x0E-0F)
Undefined

VK_SHIFT (0x10)
SHIFT key

VK_CONTROL (0x11)
CTRL key

VK_MENU (0x12)
ALT key

VK_PAUSE (0x13)
PAUSE key

VK_CAPITAL (0x14)
CAPS LOCK key

VK_KANA (0x15)
Input Method Editor (IME) Kana mode

VK_HANGUEL (0x15)
IME Hanguel mode (maintained for compatibility; use VK_HANGUL)

VK_HANGUL (0x15)
IME Hangul mode

- (0x16)
Undefined

VK_JUNJA (0x17)
IME Junja mode

VK_FINAL (0x18)
IME final mode

VK_HANJA (0x19)
IME Hanja mode

VK_KANJI (0x19)
IME Kanji mode

- (0x1A)
Undefined

VK_ESCAPE (0x1B)
ESC key

VK_CONVERT (0x1C)
IME convert

VK_NONCONVERT (0x1D)
IME nonconvert

VK_ACCEPT (0x1E)
IME accept

VK_MODECHANGE (0x1F)
IME mode change request

VK_SPACE (0x20)
SPACEBAR

VK_PRIOR (0x21)
PAGE UP key

VK_NEXT (0x22)
PAGE DOWN key

VK_END (0x23)
END key

VK_HOME (0x24)
HOME key

VK_LEFT (0x25)
LEFT ARROW key

VK_UP (0x26)
UP ARROW key

VK_RIGHT (0x27)
RIGHT ARROW key

VK_DOWN (0x28)
DOWN ARROW key

VK_SELECT (0x29)
SELECT key

VK_PRINT (0x2A)
PRINT key

VK_EXECUTE (0x2B)
EXECUTE key

VK_SNAPSHOT (0x2C)
PRINT SCREEN key

VK_INSERT (0x2D)
INS key

VK_DELETE (0x2E)
DEL key

VK_HELP (0x2F)
HELP key

(0x30)
0 key

(0x31)
1 key

(0x32)
2 key

(0x33)
3 key

(0x34)
4 key

(0x35)
5 key

(0x36)
6 key

(0x37)
7 key

(0x38)
8 key

(0x39)
9 key

- (0x3A-40)
Undefined

(0x41)
A key

(0x42)
B key

(0x43)
C key

(0x44)
D key

(0x45)
E key

(0x46)
F key

(0x47)
G key

(0x48)
H key

(0x49)
I key

(0x4A)
J key

(0x4B)
K key

(0x4C)
L key

(0x4D)
M key

(0x4E)
N key

(0x4F)
O key

(0x50)
P key

(0x51)
Q key

(0x52)
R key

(0x53)
S key

(0x54)
T key

(0x55)
U key

(0x56)
V key

(0x57)
W key

(0x58)
X key

(0x59)
Y key

(0x5A)
Z key

VK_LWIN (0x5B)
Left Windows key (Microsoft Natural keyboard)

VK_RWIN (0x5C)
Right Windows key (Natural keyboard)

VK_APPS (0x5D)
Applications key (Natural keyboard)

- (0x5E)
Reserved

VK_SLEEP (0x5F)
Computer Sleep key

VK_NUMPAD0 (0x60)
Numeric keypad 0 key

VK_NUMPAD1 (0x61)
Numeric keypad 1 key

VK_NUMPAD2 (0x62)
Numeric keypad 2 key

VK_NUMPAD3 (0x63)
Numeric keypad 3 key

VK_NUMPAD4 (0x64)
Numeric keypad 4 key

VK_NUMPAD5 (0x65)
Numeric keypad 5 key

VK_NUMPAD6 (0x66)
Numeric keypad 6 key

VK_NUMPAD7 (0x67)
Numeric keypad 7 key

VK_NUMPAD8 (0x68)
Numeric keypad 8 key

VK_NUMPAD9 (0x69)
Numeric keypad 9 key

VK_MULTIPLY (0x6A)
Multiply key

VK_ADD (0x6B)
Add key

VK_SEPARATOR (0x6C)
Separator key

VK_SUBTRACT (0x6D)
Subtract key

VK_DECIMAL (0x6E)
Decimal key

VK_DIVIDE (0x6F)
Divide key

VK_F1 (0x70)
F1 key

VK_F2 (0x71)
F2 key

VK_F3 (0x72)
F3 key

VK_F4 (0x73)
F4 key

VK_F5 (0x74)
F5 key

VK_F6 (0x75)
F6 key

VK_F7 (0x76)
F7 key

VK_F8 (0x77)
F8 key

VK_F9 (0x78)
F9 key

VK_F10 (0x79)
F10 key

VK_F11 (0x7A)
F11 key

VK_F12 (0x7B)
F12 key

VK_F13 (0x7C)
F13 key

VK_F14 (0x7D)
F14 key

VK_F15 (0x7E)
F15 key

VK_F16 (0x7F)
F16 key

VK_F17 (0x80H)
F17 key

VK_F18 (0x81H)
F18 key

VK_F19 (0x82H)
F19 key

VK_F20 (0x83H)
F20 key

VK_F21 (0x84H)
F21 key

VK_F22 (0x85H)
F22 key

VK_F23 (0x86H)
F23 key

VK_F24 (0x87H)
F24 key

- (0x88-8F)
Unassigned

VK_NUMLOCK (0x90)
NUM LOCK key

VK_SCROLL (0x91)
SCROLL LOCK key

(0x92-96)
OEM specific

- (0x97-9F)
Unassigned

VK_LSHIFT (0xA0)
Left SHIFT key

VK_RSHIFT (0xA1)
Right SHIFT key

VK_LCONTROL (0xA2)
Left CONTROL key

VK_RCONTROL (0xA3)
Right CONTROL key

VK_LMENU (0xA4)
Left MENU key

VK_RMENU (0xA5)
Right MENU key

VK_BROWSER_BACK (0xA6)
Windows 2000/XP: Browser Back key

VK_BROWSER_FORWARD (0xA7)
Windows 2000/XP: Browser Forward key

VK_BROWSER_REFRESH (0xA8)
Windows 2000/XP: Browser Refresh key

VK_BROWSER_STOP (0xA9)
Windows 2000/XP: Browser Stop key

VK_BROWSER_SEARCH (0xAA)
Windows 2000/XP: Browser Search key

VK_BROWSER_FAVORITES (0xAB)
Windows 2000/XP: Browser Favorites key

VK_BROWSER_HOME (0xAC)
Windows 2000/XP: Browser Start and Home key

VK_VOLUME_MUTE (0xAD)
Windows 2000/XP: Volume Mute key

VK_VOLUME_DOWN (0xAE)
Windows 2000/XP: Volume Down key

VK_VOLUME_UP (0xAF)
Windows 2000/XP: Volume Up key

VK_MEDIA_NEXT_TRACK (0xB0)
Windows 2000/XP: Next Track key

VK_MEDIA_PREV_TRACK (0xB1)
Windows 2000/XP: Previous Track key

VK_MEDIA_STOP (0xB2)
Windows 2000/XP: Stop Media key

VK_MEDIA_PLAY_PAUSE (0xB3)
Windows 2000/XP: Play/Pause Media key

VK_LAUNCH_MAIL (0xB4)
Windows 2000/XP: Start Mail key

VK_LAUNCH_MEDIA_SELECT (0xB5)
Windows 2000/XP: Select Media key

VK_LAUNCH_APP1 (0xB6)
Windows 2000/XP: Start Application 1 key

VK_LAUNCH_APP2 (0xB7)
Windows 2000/XP: Start Application 2 key

- (0xB8-B9)
Reserved

VK_OEM_1 (0xBA)
Used for miscellaneous characters; it can vary by keyboard.

Windows 2000/XP: For the US standard keyboard, the ';:' key

VK_OEM_PLUS (0xBB)
Windows 2000/XP: For any country/region, the '+' key

VK_OEM_COMMA (0xBC)
Windows 2000/XP: For any country/region, the ',' key

VK_OEM_MINUS (0xBD)
Windows 2000/XP: For any country/region, the '-' key

VK_OEM_PERIOD (0xBE)
Windows 2000/XP: For any country/region, the '.' key

VK_OEM_2 (0xBF)
Used for miscellaneous characters; it can vary by keyboard.

Windows 2000/XP: For the US standard keyboard, the '/?' key

VK_OEM_3 (0xC0)
Used for miscellaneous characters; it can vary by keyboard.

Windows 2000/XP: For the US standard keyboard, the '`~' key

- (0xC1-D7)
Reserved

- (0xD8-DA)
Unassigned

VK_OEM_4 (0xDB)
Used for miscellaneous characters; it can vary by keyboard.

Windows 2000/XP: For the US standard keyboard, the '[{' key

VK_OEM_5 (0xDC)
Used for miscellaneous characters; it can vary by keyboard.

Windows 2000/XP: For the US standard keyboard, the '\|' key

VK_OEM_6 (0xDD)
Used for miscellaneous characters; it can vary by keyboard.

Windows 2000/XP: For the US standard keyboard, the ']}' key

VK_OEM_7 (0xDE)
Used for miscellaneous characters; it can vary by keyboard.

Windows 2000/XP: For the US standard keyboard, the 'single-quote/double-quote' key

VK_OEM_8 (0xDF)
Used for miscellaneous characters; it can vary by keyboard.

- (0xE0)
Reserved

(0xE1)
OEM specific

VK_OEM_102 (0xE2)
Windows 2000/XP: Either the angle bracket key or the backslash key on the RT 102-key keyboard

(0xE3-E4)
OEM specific

VK_PROCESSKEY (0xE5)
Windows 95/98/Me, Windows NT 4.0, Windows 2000/XP: IME PROCESS key

(0xE6)
OEM specific

VK_PACKET (0xE7)
Windows 2000/XP: Used to pass Unicode characters as if they were keystrokes. The VK_PACKET key is the low word of a 32-bit Virtual Key value used for non-keyboard input methods. For more information, see Remark in KEYBDINPUT, SendInput, WM_KEYDOWN, and WM_KEYUP

- (0xE8)
Unassigned

(0xE9-F5)
OEM specific

VK_ATTN (0xF6)
Attn key

VK_CRSEL (0xF7)
CrSel key

VK_EXSEL (0xF8)
ExSel key

VK_EREOF (0xF9)
Erase EOF key

VK_PLAY (0xFA)
Play key

VK_ZOOM (0xFB)
Zoom key

VK_NONAME (0xFC)
Reserved

VK_PA1 (0xFD)
PA1 key

VK_OEM_CLEAR (0xFE)
Clear key

Monday, April 5, 2010

LPC17xx GPIO basic

Depend on LPC17xx version the pinouts may be different. I am using 100-pin LPC1768 as an example.
Reference document: LPC17xx User manual
Require #include header lpc17xx.h
Pins on LPC1768 are divided into 5 groups (PORT) starting from 0 to 4.
Pin naming convention: P0.0 (group 0, pin 0) or (Port 0, Pin 0)
Note: if I refer to a page number, that page number is from LPC17xx User manual
Each pin has 4 operating modes: GPIO(default), 1st alternate function, 2nd alternate function, 3rd alternate function.
All GPIO pins are powered automatically so we do not need to turn on the pin power supply.

1. Pin function setting
The register LPC_PINCON control operating mode of these pins. LPC_PINCON->PINSEL0[1:0] control PIN 0.0 operating mode (page 106/835)
...
LPC_PINCON->PINSEL0[31:30] control PIN 0.15 operating mode
LPC_PINCON->PINSEL1[1:0] control PIN 0.16 operating mode
...
LPC_PINCON->PINSEL1[29:28] control PIN 0.30 operating mode
LPC_PINCON->PINSEL2[1:0] control PIN 1.0 operating mode
...
LPC_PINCON->PINSEL2[31:30] control PIN 1.15 operating mode
LPC_PINCON->PINSEL3[1:0] control PIN 1.16 operating mode
...
LPC_PINCON->PINSEL3[31:30] control PIN 1.31 operating mode
...
LPC_PINCON->PINSEL9[25:24] control PIN 4.28 operating mode
LPC_PINCON->PINSEL9[27:26] control PIN 4.29 operating mode

Note: Some register bits are reserved and are not used to control a pin. For example,
LPC_PINCON->PINSEL9[23:0] are reserved
LPC_PINCON->PINSEL9[31:28] are reserved

Bit Values Function
00 GPIO function
01 1st alternate function
10 2nd alternate function
11 3rd alternate function

Example:
To set pin 0.3 as GPIO (set corresponding bit to 00)
LPC_PINCON->PINSEL0 &=~((1 <<7)|(1<<6));

To set pin 0.3 as ADC channel 0.6 (2nd alternate function, set corresponding bit to 10)
LPC_PINCON->PINSEL0 |=((1 <<7)|(0<<6)); // you may omit (0<<6)

2. Pin direction setting
Register LPC_GPIOn->FIODIR[31:0] control the pin input/output where n is the pin group (0-4)
To set a pin as output, set the corresponding bit to 1. To set a pin as input, set the corresponding bit to 0. By default, all pins are set as input (all bits are 0).

Example:
To set pin 0.3 as output
LPC_GPIO0->FIODIR |= (1<<3);

3. A pin is set as output
Pin digital high/low setting
LPC_GPIOn->FIOSET is used to turn a pin to HIGH (page 122/835)
Register LPC_GPIOn->FIOCLR is used to turn a pin to LOW
To turn a pin to digital 1 (high), set the corresponding bit of LPC_GPIOn->FIOSET to 1. To turn a pin to digital 0 (low), set the corresponding bit of LPC_GPIOn->FIOCLR to 1.

Example:
Turn pin 0.3 to high
LPC_GPIO0->FIOSET |= (1<<3);
If we set LPC_GPIOn->FIOSET bit to 0, there is no effect
Turn pin 0.3 to low
LPC_GPIO0->FIOCLR |= (1<<3);
If we set LPC_GPIOn->FIOCLR bit to 0, there is no effect

4. A pin is set to input
a. Read a pin value
Register LPC_GPIOn->FIOPIN stores the current pin state. (page 125/835)
The corresponding bit is 1 indicates that the pin is driven high

Example:
To read current pin 0.3 state
value = ((LPC_GPIO0->FIOPIN & (1 <<3))>> 3);

Note:
Write a 1/0 to a corresponding bit in LPC_GPIOn->FIOPIN can change the output of the pin to 1/0 but it is not recommended. We should use LPC_GPIOn->FIOSET and LPC_GPIOn->FIOCLR instead.

b. Pin internal pull up setting
Register LPC_PINCON->PINMODEn is used to set up a pin internal pull up
LPC_PINCON->PINMODE0[1:0] control P0.0 internal pull up
...
LPC_PINCON->PINMODE0[31:30] control P0.15 internal pull up

Please see LPC_PINCON->PINSELn for the full list or page 110/835

Bit values Pin mode
00 on-chip pull-up resistor enabled
01 repeater mode,see page 103/835
10 tri-state mode, neither pull-up nor pull-down resistor enabled
11 on-chip pull-down resistor enabled

Example
By default all pins which are set as input has internal pull-up on (00)
To disable internal pull-up on pin 0.3
LPC_PINCON->PINSEL0 |= (1 << 7);

5. Using GPIO interrupt, only pin group 0 and 2 are used with pin interrupt
a. Falling edge interrupt
Register LPC_GPIOINT->IOxIntEnF is used to enable falling edge detected interrupt, in which x is the group number, either 0 or 2. To turn on falling edge interrupt of a pin, set the corresponding pin to 1.

Example

To enable pin 0.3 falling edge interrupt
LPC_GPIOINT->IO0IntEnF |= (1 << 3);

b. Raising edge interrupt
Register LPC_GPIOINT->IOxIntEnR is used to enable raising edge detected interrupt, in which x is the group number. To turn on raising edge interrupt of a pin, set the corresponding pin to 1.

Example

To enable pin 0.3 and 0.5 raising edge interrupt
LPC_GPIOINT->IO0IntEnR |= ((1 << 3)| (1 << 5));


c. All GPIO interrupts are connected to to EINT3 interrupt source. You need to turn EINT3_IRQn on in order to use GPIO interrupt.
NVIC_EnableIRQ(EINT3_IRQn);

d. Interrupt handler subroutine
Add this subroutine to your code. Every time the GPIO interrupts are fired (regardless of which pin), this subroutine is called.
void EINT3_IRQHandler (void)
{

}

Register LPC_GPIOINT->IOxIntStatF[31:0] has the status of which pin falling edge interrupt was fired.
Register LPC_GPIOINT->IOxIntStatR[31:0] has the status of which pin raising edge interrupt was fired.
Register LPC_GPIOINT->IOxIntClr[31:0] is used to clear the status of a pin interrupt. To clear the status bit, write 1 to the corresponding bit.

Example
To check if pin 0.3 interrupt was fired or pin 0.5 interrupt was fired
void EINT3_IRQHandler (void)
{
  if ((LPC_GPIOINT->IO0IntStatR & (1 << 3)) == (1 << 3))
  {
  //raising edge interrupt on pin 0.3 was fired
  LPC_GPIOINT->IO0IntClr |= (1 << 3); // clear the status
  //do your task
 
  return;
  }
 
  if ((LPC_GPIOINT->IO0IntStatR & (1 << 5)) == (1 << 5))
  {
  //raising edge interrupt on pin 0.5 was fired
  LPC_GPIOINT->IO0IntClr |= (1 << 5); // clear the status
  //do your task
 
  return;
  }
}