AVR Freaks

I have USB-USART module based on PL2303 chip, so one WiFi ESP8266 I connected directly to it -> Try to send "AT" command -> I get responce from module - (41 F5) hex meggase.

Another WiFi ESP8266 I connect to ATmega16 -> Rx (module 7 pin) to ATmega16 TxD PD1, Tx (module 2 pin) to ATmega16 RxD PD0.

As power supply I use board (my own design) connected to 12V and lower down to 5V and 3.3V. I tested voltage from it to WiFi ESP8266 -> 3.2V

I connected USB-USART PL2303 module to my ATmega16 -> Try to send some symbols -> ISR (USART_RXC_vect) working. 

Inside ISR (USART_RXC_vect) I make LED blink -> it does. And display symbols send on LED display -> it working. (some issue with ASCII code but it manageable).

I can't get any responce from module after I send from ATmega16 simmple "AT" command.

My board:

ATmega16 with external crystal 8MHz.

I blink with LED by code:

#define LED_PORT PORTB
#define LED_DIR DDRB
#define LED_PIN 0
ISR (USART_RXC_vect) {
	usartRxBuf = UDR;

	LED_PORT |= (1<<LED_PIN);
	_delay_ms(500);
	LED_PORT &= ~(1<<LED_PIN);
	_delay_ms(500);

	LCD_SetCursor(3, 0); LCD_DisplaySymbol(usartRxBuf);
	FlushBuf();
}

With USB-USART module based on PL2303 chip I use Terminal v1.9b -> not all ASCII display correct, for example RU simbols.

void USART_Init(unsigned int speed) {
	UBRRH = (unsigned char)(speed>>8);
	UBRRL = (unsigned char)speed;
	UCSRB |= (1<<RXEN)|(1<<TXEN); // Enable USART 
	UCSRB |= (1<<RXCIE); // Enable ISR (USART_RXC_vect)
	UCSRA |= (1<<U2X);// Double clock rate
	UCSRC |= (1<<URSEL)|(1<<USBS)|(1<<UCSZ1)|(1<<UCSZ0); // Asinc (URSEL = 0), turn off parity (UPM1 = 0, UOM0 = 0), 2 stop bits (USBS = 1), package 8 bits (UCSZ1 = 1, UCSZ0 = 1)
}

I use USART 115.2K speed:

int main(void) {
	USART_Init(8);

To hight speed for WiFi ESP8266? Should speed be lower or hight????

I try to use Termite 3.4 (by CompuPhase).

I get module version:

AT version:1.1.0.0(May 11 2016 18:09:56)
SDK version:1.5.4(baaeaebb)
Ai-Thinker Technology Co. Ltd.
Jun 13 2016 11:29:20

I don't know...need to upgrade to upper version???

Some of commands returns with ERROR message (AT+CWLAP for example). 

I find issue -> I re-write USART send functions:

void USART_SendString(char * s) {
	while(*(s)!='\0') {
		USART_SendChar(*(s++));
	}
}

void USART_SendChar(unsigned char symbol) {
	while(!(UCSRA & (1<<UDRE)));
	UDR = symbol;
}

Use it like this:

void USART_Init(unsigned int speed) {
	UBRRH = (unsigned char)(speed>>8);
	UBRRL = (unsigned char)speed;
	UCSRB |= (1<<RXEN)|(1<<TXEN);
	UCSRB |= (1<<RXCIE);
	UCSRA |= (1<<U2X);
	UCSRC |= (1<<URSEL)|(1<<USBS)|(1<<UCSZ1)|(1<<UCSZ0);
}
void USART_SendString(char * s) {
	while(*(s)!='\0') {
		USART_SendChar(*(s++));
	}
}
void USART_SendChar(unsigned char symbol) {
	while(!(UCSRA & (1<<UDRE)));
	UDR = symbol;
}

#define LED_PORT PORTB
#define LED_DIR DDRB
#define LED_PIN 0

#define SIZE_BUF 48
volatile unsigned char cycleBuf[SIZE_BUF];
volatile unsigned char tail = 0;

void FlushBuf(void) {
	tail = 0;
	cycleBuf[0] = 0;
}

ISR (USART_RXC_vect) {
	usartRxBuf = UDR;

	cycleBuf[tail] = usartRxBuf;
	tail++;

	LED_PORT |= (1<<LED_PIN);
	_delay_ms(1000);
	LED_PORT &= ~(1<<LED_PIN);
	_delay_ms(1000);

	LCD_SetCursor(3, 0);
	LCD_DisplaySymbol(usartRxBuf);
}
int main(void) {
    USART_Init(8);
    ...
    USART_SendString("AT");
    USART_SendChar(13);
    _delay_ms(5000);
    ...
    sei();
    while(1) {
        ...
    }
}

I write code as simple as I can. Now I manage to blink LED inside ISR (USART_RXC_vect) -> signal of receiving data by USART.

But I don't understant format of data recieved from ESP8266 inside ISR (USART_RXC_vect).

It is not ASCII as I guess. So how I should properly transform data received from ESP8266???? to display on LCD or else were??? data format hex, dec or string from ESP8266???

// you can't have delays like this in your isr !
// at 115200 baud, each character takes 87us to send.
// here, you will simply miss characters

	LED_PORT |= (1<<LED_PIN);
	_delay_ms(1000);
	LED_PORT &= ~(1<<LED_PIN);
	_delay_ms(1000);

// again, you can't do this here - your lcd functions will most likely take
// more than 87us. You will miss characters

	LCD_SetCursor(3, 0);
	LCD_DisplaySymbol(usartRxBuf);

I will remove LCD display info and LED blink from ISR func -> it is for test only.

USART_SendString("AT");
USART_SendChar(13);
_delay_ms(5000);

5 sec I remove also -> my issue, I miss that.

So I should form data from inside:

ISR (USART_RXC_vect)

...but use data from ESP8266 in some other point:

ISR(TIMER0_COMP_vect)
	or
ISR(TIMER0_OVF_vect) 

I will think this later.

I tested it. not working.

I have:

int main(void) {
	PORTD = 0x00;
	DDRD = 0xFF;

without it no data transfer at all. Configure portD for output. Could it be issue???

Yes,  ATmega16 -> TxD PD1, RxD PD0.

EEPROM for view results of transfer only..allredy remove it from code.

int main(void) {
	PORTD = 0x00;
	DDRD = 0xFF;		
	
	USART_Init(16);
	
	sei();
	
	USART_SendChar(65);
	USART_SendChar(84);
	
	while(1) {		

And on Termite terminal prog I get incorect results of transfering data. So I guess USART not working or settings not good.

65 decimal for 'A'

85 decimal for 'T'

...same as:

USART_SendChar('A');
USART_SendChar('T');

I tested all variables. Nothing work.

When I connect ESP8266 to  USB-USART PL2303 module and send from Termite 'AT' command I get responce 'OK'. PROBLES is USART on ATmega16.

No I did not. I typed I switch to 16MHz extermal crystal but nothig changed.

I switch to 16MHz external and set settings to 115.2K by set 2.1%.

But I alse set 

USART_Init(16);	

...with U2X=1 error is 2.1%

But I also set baud rate to 2400 on ATmega16 by 

USART_Init(832);	

and Termite -> with U2X=1 error is 0.0%

Transfer failed.

Tanks all for help. Some good ideas I will use like 'Circular Buffer ')