Web Browser Chat Between 2 PCs Over RS232 Serial Port

Simple chat messaging between 2 PC's using OLIMEX PX128A1 board running XMEGA acorn micro kernel. Two UART chennels are used to connect 2 PCs that run  Chrome browser Chat UI as clients written in vuejs. In contrast to RS232Chat that is using Windows exe as UI client, here the client is rendered in Chrome Browser and Serial API is used to set up RS232 channel in both directions.

OLIMEX PX128A1 board runs 4 tasks concurrently within Acorn micro kernel, observing the Producer - Consumer design pattern to facilitate asynchronous communication within the 2 UART channels and LCD control screen. 

Browser based UI client running on both PC's. Web Serial API and vuejs were used to develop it thus making the UI completely agnostic to the host OS.

Incoming bytes from Rx1 Interrupt handler channel D(first PC) are fed into a circular queue-like buffer dedicated to channel D.

Same task dispatches bytes to channel E

usart_task_D:
        //***init buffer channel D0 
	ldi ZL,low(usartD0_16)
	ldi ZH,high(usartD0_16)
	rcall spc_queue16_init


	/* USARTD0, 8 Data bits, No Parity, 1 Stop bit. */
	rcall usart_init_d_int


_THRESHOLD_BARRIER_WAIT  InitTasksBarrier,TASKS_NUMBER


_INTERRUPT_DISPATCHER_INIT temp,RX1_INT_ID


main_usart_d:
/*RECEIVE from channel #1*/
    _INTERRUPT_WAIT RX1_INT_ID
		ldi ZL,low(usartD0_16)
		ldi ZH,high(usartD0_16)	  	
		ldi axl,low(USARTD0_QUEUE_MAX_SIZE)
		ldi axh,high(USARTD0_QUEUE_MAX_SIZE)		
		rcall spc_queue16_pop
	_INTERRUPT_END RX1_INT_ID


	;queue output is in `dxh:dxl`
    brts wait_rx_int_d		;is empty queue?
    rjmp main_usart_d		


wait_rx_int_d:
/*SEND to channel #2*/
    rcall usart_send_bytes_e


rjmp main_usart_d	

 USARTD0_Rx:
_PRE_INTERRUPT
        push ZH
	push ZL
	push cxh
	push cxl
	push dxh
	push dxl
	push axh
	push axl
        push argument
	push bxl
	push bxh
	push r0
	push r1
        push r2
	push r3


	;read USART data in 16bit buffer
        lds dxl,USARTD0_DATA


	ldi ZL,low(usartD0_16)
	ldi ZH,high(usartD0_16)	  	
	ldi axl,low(USARTD0_QUEUE_MAX_SIZE)
	ldi axh,high(USARTD0_QUEUE_MAX_SIZE)
	
	rcall spc_queue16_push_from_isr	


	pop r3
	pop r2
	pop r1
	pop r0
	pop bxh
	pop bxl
	pop argument
	pop axl
	pop axh
	pop dxl
	pop dxh
	pop cxl
	pop cxh
	pop ZL
	pop ZH


_keDISPATCH_DPC RX1_INT_ID

Acorn micro-kernel synchronizes access to shared queue structures for both channels

Incoming bytes from Rx2 Interrupt handler channel E(second PC) are fed into a circular queue-like buffer dedicated to channel E.

Same task dispatches bytes to channel D

usart_task_E:
    	ldi ZL,low(usartE0_16)
	ldi ZH,high(usartE0_16)
	rcall spc_queue16_init


	/* USARTE0, 8 Data bits, No Parity, 1 Stop bit. */
	rcall usart_init_e_int
	
_THRESHOLD_BARRIER_WAIT  InitTasksBarrier,TASKS_NUMBER


_INTERRUPT_DISPATCHER_INIT temp,RX2_INT_ID


main_usart_e:
    ;pop from other channel
	_INTERRUPT_WAIT RX2_INT_ID
		ldi ZL,low(usartE0_16)
		ldi ZH,high(usartE0_16)	  	
		ldi axl,low(USARTE0_QUEUE_MAX_SIZE)
		ldi axh,high(USARTE0_QUEUE_MAX_SIZE)		
		rcall spc_queue16_pop
	_INTERRUPT_END RX2_INT_ID


	;queue output is in `dxh:dxl`
        brts wait_rx_int_e		;is empty queue?
        rjmp main_usart_e


wait_rx_int_e:    
	rcall usart_send_byte_d			;cross channel


rjmp main_usart_e

 USARTE0_Rx:
_PRE_INTERRUPT
        push ZH
	push ZL
	push cxh
	push cxl
	push dxh
	push dxl
	push axh
	push axl
        push argument
	push bxl
	push bxh
	push r0
	push r1
        push r2
	push r3


	;read USART data in 16bit buffer
        lds dxl,USARTE0_DATA


	ldi ZL,low(usartE0_16)
	ldi ZH,high(usartE0_16)	  	
	ldi axl,low(USARTE0_QUEUE_MAX_SIZE)
	ldi axh,high(USARTE0_QUEUE_MAX_SIZE)
	
	rcall spc_queue16_push_from_isr	


	pop r3
	pop r2
	pop r1
	pop r0
	pop bxh
	pop bxl
	pop argument
	pop axl
	pop axh
	pop dxl
	pop dxh
	pop cxl
	pop cxh
	pop ZL
	pop ZH


_keDISPATCH_DPC RX2_INT_ID

Acorn micro-kernel synchronizes access to shared queue structures for both channels