usb_to_serial.asm

usb serial converter

Get_Device_Status:
    mov     A, RAM                          ;
    mov     [ram_or_rom], A                 ;

    mov     A, 02h                          ;
    mov     [data_count], A                 ;

    mov     A, device_status                ;
    jmp     Execute                         ;

;****************************************************************
; REQUEST: Get_Descriptor
;****************************************************************
; There are five descriptor types. The descriptor type will 
; be in the high byte of value. The standard request to a 
; device supports three of these types: device, configuration
; and string. The standard request does not support interface
; or endpoint descriptor. The String descriptor has also 
; a subset of different descriptor and those are chosen by 
; the low byte of value. There are also two additional
; descriptors added in the case of a this HID device, the
; HID descriptor, and the report descriptor
;****************************************************************

Get_Descriptor:
    mov     X, SIZEOF_REPORT_ID_TABLE       ; get table size

;   inc     [control_read_counter]          ;

;   mov     A, [control_read_counter]       ;
;   cmp     A, 25h                          ;
;   jnz     .loop                           ;

;   halt                                    ;

.loop:
    dec     X                               ;
    jc      Send_Stall                      ; if we have traversed the table then stall
    
    dec     X                               ;

    mov     A, X                            ; get current position
    index   report_id_table                 ; fetch value from rom

    cmp     A, [value_hi]                   ; is there a match
    jnz     .loop                           ; if not then try next entry
    
    mov     A, X                            ;
    index   (report_id_table + 1)           ; check the low byte

    cmp     A, [value]                      ; is there a match
    jnz     .loop                           ; if not then try next entry
    
    mov     A, ROM                          ;
    mov     [ram_or_rom], A                 ; to load data from ROm

    mov     A, X                            ; we have found the entry
    jacc    Report_Jump_Table               ; jump to the proper place

;****************************************************************
; REQUEST: Get_Device_Descriptor
;****************************************************************

Get_Device_Descriptor:
    mov     A, SIZEOF_DEVICE_DESCRIPTOR     ; 
    mov     [data_count], A                 ; 

    mov     A, (device_descriptor - control_read_table) ;

    jmp     Execute                         ; 

;****************************************************************
; REQUEST: Get_Configuration_Descriptor
;****************************************************************
; Returns the configuration, interface, and endpoint descriptors.
;****************************************************************

Get_Configuration_Descriptor:
    mov     A, SIZEOF_ALL_CONFIGURATION_DESCRIPTORS ;
    mov     [data_count], A                 ;

    mov     A, (configuration_descriptor - control_read_table) ;
    jmp     Execute                         ;

;****************************************************************
; REQUEST: Get_Language_String_Descriptor
;****************************************************************

Get_Language_String_Descriptor:
    mov     A, SIZEOF_LANGUAGE_STRING       ;
    mov     [data_count], A                 ;

    mov     A, (language_string - control_read_table) ;
    jmp     Execute                         ;

;****************************************************************
; REQUEST: Get_Manufacturer_String_Descriptor
;****************************************************************

Get_Manufacturer_String_Descriptor:    
    mov     A, SIZEOF_MANUFACTURER_STRING   ;
    mov     [data_count], A                 ;

    mov     A, (manufacturer_string - control_read_table) ;
    jmp     Execute                         ;

;****************************************************************
; REQUEST: Get_Product_String_Descriptor
;****************************************************************

Get_Product_String_Descriptor:
    mov     A, SIZEOF_PRODUCT_STRING        ;
    mov     [data_count], A                 ;

    mov     A, (product_string - control_read_table) ;
    jmp     Execute                         ;

;****************************************************************
; REQUEST: Get_Serial_String_Descriptor
;****************************************************************

Get_Serial_String_Descriptor:
    mov     A, SIZEOF_SERIAL_STRING         ;
    or      A, 00h                          ;
    jz      Send_Stall                      ;
    
    mov     [data_count], A                 ;

    mov     A, (serial_string - control_read_table) ;
    jmp     Execute                         ;

;****************************************************************
; REQUEST: Get_Configuration_String_Descriptor
;****************************************************************

Get_Configuration_String_Descriptor:
    mov     A, SIZEOF_CONFIGURATION_STRING  ;
    mov     [data_count], A                 ;

    mov     A, (configuration_string - control_read_table) ;
    jmp     Execute                         ;

;****************************************************************
; REQUEST: Get_Interface_String_Descriptor
;****************************************************************

Get_Interface_String_Descriptor:
    mov     A, SIZEOF_INTERFACE_STRING      ;
    mov     [data_count], A                 ;

    mov     A, (interface_string - control_read_table) ;
    jmp     Execute                         ;

;****************************************************************
; REQUEST: Get_Hid_Descriptor
;****************************************************************

Get_Hid_Descriptor:
    mov     A, SIZEOF_HID_DESCRIPTOR        ;
    mov     [data_count], A                 ;

    mov     A, (hid_descriptor - control_read_table) ;
    jmp     Execute                         ;

;****************************************************************
; REQUEST: Get_Hid_Report_Descriptor
;****************************************************************

Get_Hid_Report_Descriptor:
    mov     A, SIZEOF_HID_REPORT_DESCRIPTOR ;
    mov     [data_count], A                 ;

    mov     A, (hid_report_descriptor - control_read_table) ;
    jmp     Execute                         ;

;****************************************************************
; REQUEST: Get_Configuration
;****************************************************************

Get_Configuration:
    mov     A, RAM                          ;
    mov     [ram_or_rom], A                 ;

    mov     A, 01h                          ;
    mov     [data_count], A                 ;

    mov     A, configuration                ;
    jmp     Execute                         ;

;****************************************************************
; REQUEST: Get_Interface_Status
;****************************************************************

Get_Interface_Status:
    mov     A, RAM                          ;
    mov     [ram_or_rom], A                 ;

    mov     A, 02h                          ;
    mov     [data_count], A                 ;

    mov     A, zero_register                ;
    jmp     Execute                         ;

;****************************************************************
; REQUEST: Get_Interface
;****************************************************************

Get_Interface:
    mov     A, RAM                          ;
    mov     [ram_or_rom], A                 ;

    mov     A, 01h                          ;
    mov     [data_count], A                 ;

    mov     A, zero_register                ;
    jmp     Execute                         ;

;****************************************************************
; REQUEST: Get_Endpoint_Status
;****************************************************************

Get_Endpoint_Status:
    mov     A, [index_hi]                   ; 
    cmp     A, 00h                          ;
    jnz     Send_Stall                      ; 

    mov     A, RAM                          ;
    mov     [ram_or_rom], A                 ;

    mov     A, 02h                          ;
    mov     [data_count], A                 ;
    
;----------------------------------------------------------------

    ; If the request is for endpoint 0, send
    ; ep0_status (ep0_status is always 0.)
    
    mov     A, [index]                      ; 
    and     A, 7Fh                          ; 

    mov     A, zero_register                ;
    jz      Execute                         ;

;----------------------------------------------------------------

    ; If the device is unconfigured, stall
    ; this request for endpoints > 0.
    
    mov     A, [configuration]              ; 
    cmp     A, UNCONFIGURED                 ; 
    jz      Send_Stall                      ; 
    
    ; Otherwise, send the requested endpoint
    ; status.
    
    mov     A, [index]                      ;
    and     A, 7Fh                          ; 
    cmp     A, 01h                          ; 
    jnz     .Ge2                            ;

    mov     A, ep1_status                   ;
    jmp     Execute                         ;

.Ge2:
    cmp     A, 02h                          ; if it's not endpoint 2 then 
    jnz     Send_Stall                      ;

    mov     A, ep2_status                   ; send ep2 status 
    jmp     Execute                         ;

;****************************************************************
; REQUEST: Set_Report
;****************************************************************

Set_Report:
    mov     A, ACK_OUT_STATUS_IN            ;
    mov     [ep0_next_mode], A              ;

    ret                                     ;

;****************************************************************
; REQUEST: Set_Idle
;****************************************************************

Set_Idle:
	mov     A, [value_hi]                   ;
	mov     [idle],  A                      ;

	call    No_Data_Control                 ;

	ret                                     ;

;****************************************************************
; REQUEST: Set_Protocol
;****************************************************************

Set_Protocol:
    mov     A, [value]                      ;
    mov     [protocol], A                   ;

    call    No_Data_Control                 ;

    ret                                     ;

;****************************************************************
; REQUEST: Get_Report
;****************************************************************

Get_Report:
    mov     A, RAM                          ;
    mov     [ram_or_rom], A                 ;

    mov     A, 05h                          ;
    mov     [data_count], A                 ;

    mov     A, control_report               ;
    jmp     Execute                         ;

;****************************************************************
; REQUEST: Get_Idle
;****************************************************************

Get_Idle:
    mov     A, RAM                          ;
    mov     [ram_or_rom], A                 ;

	mov     A, 01h                          ;
	mov     [data_count], A                 ;

	mov     A, idle                         ;

	jmp     Execute                         ;

;****************************************************************
; REQUEST: Get_Protocol
;****************************************************************

Get_Protocol:
    mov     A, RAM                          ;
    mov     [ram_or_rom], A                 ;

    mov     A, 01h                          ;
    mov     [data_count], A                 ;

    mov     A, protocol                     ;
    jmp     Execute                         ;

;****************************************************************
; FUNCTION: No_Data_Control
;****************************************************************

No_Data_Control:

    mov     A, STATUS_IN_ONLY               ; set next mode to react to STATUS IN
    mov     [ep0_next_mode],A               ;

    ret                                     ;

;****************************************************************
; FUNCTION: No_Data_Control_Wait
;****************************************************************

No_Data_Control_Wait:
    mov     A, STATUS_IN_ONLY               ; enable TX0 IN
    iowr    EP0_MODE                        ;

    ; wait for the zero-length transfer to complete
No_Data_Control_Loop:
    iowr    WDT                             ;

    iord    EP0_MODE