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kurtzweber
Joined: 18 Oct 2012
Posts: 4
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| USB keyboard with 18f14k50 |
 Posted: Mon Oct 22, 2012 6:24 am |
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Hello!
I'm working on a project with a 18f14k50 PIC. I need to implement a keyboard HID device and I'm working with the provided examples.
My first attempt is to simply send "Hello" string every 10sec, here's my code:
| Code: | #include "PwdHID.h"
#include "PwdHID_desc.h"
#include <pic18_usb.h>
#include <usb_bootloader.h>
#include <usb.c>
#define KB_MODIFIER_LEFT_SHIFT 2
void main() {
set_tris_c(0x00);
output_low(LED_RED);
output_low(LED_YELLOW);
output_low(LED_GREEN);
usb_init_cs();
while(TRUE) {
usb_task();
if(usb_enumerated()) {
output_high(LED_GREEN);
sendChar('H');
sendChar('e');
sendChar('l');
sendChar('l');
sendChar('o');
sendChar('\n');
delay_ms(10000);
}
}
}
void sendChar(char c) {
unsigned int8 tx_msg[7];
unsigned int8 leds;
unsigned int16 scancode;
if (usb_tbe(1)) {
memset(tx_msg, 0x00, sizeof(tx_msg));
scancode = ToHidKeyboardScancode(c);
if(bit_test(scancode, 8)) tx_msg[0] = KB_MODIFIER_LEFT_SHIFT;
tx_msg[2] = scancode;
usb_put_packet(1, tx_msg, sizeof(tx_msg), USB_DTS_TOGGLE);
}
if(usb_kbhit(1)) usb_get_packet(1, &leds, 1);
}
unsigned int16 ToHidKeyboardScancode(char c)
{
unsigned int16 shift = 0;
if ((c>='A')&&(c<='Z'))
{
c = tolower(c);
shift = 0x100;
}
if ((c>='a')&&(c<='z'))
{
return(((c-='a')+4)|shift);
}
if ((c>='1')&&(c<='9'))
{
return((c-='0')+0x1D);
}
switch(c)
{
case '!': return(0x11E);
case '@': return(0x11F);
case '#': return(0x120);
case '$': return(0x121);
case '%': return(0x122);
case '^': return(0x123);
case '&': return(0x124);
case '*': return(0x125);
case '(': return(0x126);
case ')': return(0x127);
case '0': return(0x27);
case '\n': return(0x28); //enter
case '\r': return(0x28); //enter
case '\b': return(0x2A); //backspace
case '\t': return(0x2B); //tab
case ' ': return(0x2C); //space
case '_': return(0x12D);
case '-': return(0x2D);
case '+': return(0x12E);
case '=': return(0x2E);
case '{': return(0x12F);
case '[': return(0x2F);
case '}': return(0x130);
case ']': return(0x30);
case '|': return(0x131);
case '\\': return(0x31);
case ':': return(0x133);
case ';': return(0x33);
case '"': return(0x134);
case '\'': return(0x34);
case '~': return(0x135);
case '`': return(0x35);
case '<': return(0x136);
case ',': return(0x36);
case '>': return(0x137);
case '.': return(0x37);
case '?': return(0x138);
case '/': return(0x38);
}
} |
When I run it, my PC correctly detect the new device but it starts to send only 'H':
Where am I wrong?
Thanks! |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19559
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| Posted: Mon Oct 22, 2012 7:08 am |
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Several little things.
First, rethink having a 10 second delay in the main loop. Have a timer interrupt 'ticking' at some convenient interval, and use this to do a countdown. USB, may run into problems if you pause this long between calling the task handler.
Big one though is that the key needs to release. You are sending a packet for the first key being pressed, and it is never released. Hence the computer will see it continuously repeating. To send a character, you need to send a key (with the required modifiers), and then release the key.
Best Wishes |
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kurtzweber
Joined: 18 Oct 2012
Posts: 4
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| Posted: Mon Oct 22, 2012 8:32 am |
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Thanks for your reply!
To release the key, I thought to send a message with all 0x00 but nothing changes:
| Quote: | // tx_msg[2:6] = an array of held down keys. a=4, b=5, etc.
// if msg[2:7]={0} then no keys are held down |
| Code: | void send_char(char c) {
unsigned int8 tx_msg[7];
unsigned int8 leds;
unsigned int16 scancode;
if (usb_tbe(1)) {
memset(tx_msg, 0x00, sizeof(tx_msg));
scancode = ToHidKeyboardScancode(c);
if(bit_test(scancode, 8)) tx_msg[0] = KB_MODIFIER_LEFT_SHIFT;
tx_msg[2] = scancode;
usb_put_packet(1, tx_msg, sizeof(tx_msg), USB_DTS_TOGGLE);
// release key
memset(tx_msg, 0x00, sizeof(tx_msg));
usb_put_packet(1, tx_msg, sizeof(tx_msg), USB_DTS_TOGGLE);
}
} |
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kurtzweber
Joined: 18 Oct 2012
Posts: 4
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| Posted: Mon Oct 22, 2012 9:36 am |
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Hello!
I added a small delay (100ms) between the two "usb_put_packet" and now it sends the key, but just the first one ('H'), both using printf() or calling the sub manually... very strange!
I changed also the delay function:
| Code: | #include "PwdHID.h"
#include "PwdHID_desc.h"
#include <pic18_usb.h>
#include <usb_bootloader.h>
#include <usb.c>
#define KB_MODIFIER_LEFT_SHIFT 2
int1 time_expired = FALSE;
unsigned int8 timer0_count;
#int_timer0
void int_timer0_handler() {
set_timer0(28036);
timer0_count++;
if(timer0_count == 100) {
time_expired = TRUE;
timer0_count = 0;
}
}
void main() {
set_tris_c(0x00);
output_low(LED_RED);
output_low(LED_YELLOW);
output_low(LED_GREEN);
setup_timer_0(T0_INTERNAL | T0_DIV_32);
set_timer0(28036);
enable_interrupts(INT_TIMER0);
enable_interrupts(GLOBAL);
usb_init_cs();
while(TRUE) {
usb_task();
if(usb_enumerated()) {
output_high(LED_GREEN);
if(time_expired) {
//printf(send_char, "Hello World!\n");
send_char('H');
send_char('e');
send_char('l');
send_char('l');
send_char('o');
time_expired = FALSE;
}
}
}
}
void send_char(char c) {
unsigned int8 tx_msg[7];
unsigned int8 leds;
unsigned int16 scancode;
if (usb_tbe(1)) {
memset(tx_msg, 0x00, sizeof(tx_msg));
scancode = ToHidKeyboardScancode(c);
if(bit_test(scancode, 8)) tx_msg[0] = KB_MODIFIER_LEFT_SHIFT;
tx_msg[2] = scancode;
usb_put_packet(1, tx_msg, sizeof(tx_msg), USB_DTS_TOGGLE);
// release key
delay_ms(100);
memset(tx_msg, 0x00, sizeof(tx_msg));
usb_put_packet(1, tx_msg, sizeof(tx_msg), USB_DTS_TOGGLE);
}
}
unsigned int16 ToHidKeyboardScancode(char c)
{
unsigned int16 shift = 0;
if ((c>='A')&&(c<='Z'))
{
c = tolower(c);
shift = 0x100;
}
if ((c>='a')&&(c<='z'))
{
return(((c-='a')+4)|shift);
}
if ((c>='1')&&(c<='9'))
{
return((c-='0')+0x1D);
}
switch(c)
{
case '!': return(0x11E);
case '@': return(0x11F);
case '#': return(0x120);
case '$': return(0x121);
case '%': return(0x122);
case '^': return(0x123);
case '&': return(0x124);
case '*': return(0x125);
case '(': return(0x126);
case ')': return(0x127);
case '0': return(0x27);
case '\n': return(0x28); //enter
case '\r': return(0x28); //enter
case '\b': return(0x2A); //backspace
case '\t': return(0x2B); //tab
case ' ': return(0x2C); //space
case '_': return(0x12D);
case '-': return(0x2D);
case '+': return(0x12E);
case '=': return(0x2E);
case '{': return(0x12F);
case '[': return(0x2F);
case '}': return(0x130);
case ']': return(0x30);
case '|': return(0x131);
case '\\': return(0x31);
case ':': return(0x133);
case ';': return(0x33);
case '"': return(0x134);
case '\'': return(0x34);
case '~': return(0x135);
case '`': return(0x35);
case '<': return(0x136);
case ',': return(0x36);
case '>': return(0x137);
case '.': return(0x37);
case '?': return(0x138);
case '/': return(0x38);
}
}
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thanks again! |
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kurtzweber
Joined: 18 Oct 2012
Posts: 4
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| Posted: Mon Oct 22, 2012 11:32 am |
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Ok solved 
you need a delay after each send... now I'm using 100ms but from the examples provided it seems you can use 10ms:
| Code: | // release key
delay_ms(100);
memset(tx_msg, 0x00, sizeof(tx_msg));
usb_put_packet(1, tx_msg, sizeof(tx_msg), USB_DTS_TOGGLE);
delay_ms(100); |
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egemenakbas
Joined: 10 Mar 2021
Posts: 2
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| Posted: Wed Mar 10, 2021 9:56 am |
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| kurtzweber wrote: | Ok solved
you need a delay after each send... now I'm using 100ms but from the examples provided it seems you can use 10ms:
| Code: | // release key
delay_ms(100);
memset(tx_msg, 0x00, sizeof(tx_msg));
usb_put_packet(1, tx_msg, sizeof(tx_msg), USB_DTS_TOGGLE);
delay_ms(100); |
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Hi, can you share ccs c project files to me?
thanks |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Mar 11, 2021 12:50 am |
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kurtzweber's last post was on Oct 22, 2012. That was many years ago.
Don't expect a reply. |
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egemenakbas
Joined: 10 Mar 2021
Posts: 2
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| Posted: Thu Mar 11, 2021 2:27 am |
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| PCM programmer wrote: | kurtzweber's last post was on Oct 22, 2012. That was many years ago.
Don't expect a reply. |
Hi, I noticed but wanted to take a chance  I need such a project. Thanks for the return. |
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temtronic
Joined: 01 Jul 2010
Posts: 9251
Location: Greensville,Ontario
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| Posted: Thu Mar 11, 2021 6:18 am |
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| You could take any PIC,add a TTL-USB module to do the same 'task'. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19559
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| Posted: Thu Mar 11, 2021 7:38 am |
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No, Jay. Most of these modules would be CDC devices, not HID devices.
He wants data as if it comes from a keyboard.
The original posted code sounds as if it was working with the changes
implemented, so it should only be a couple of seconds work to test it.
The reason he was having to add a delay, is a common 'misunderstanding' of
how key scan codes work. To actually simulate a key being typed, you have
to send the 'key scan code', and then a 'key released' code. By sending just
the scan code, the system instead waits for the key repeat interval, and
then 'sees' the key. Hence the delay being needed. |
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