Add activity spinner

bme280_util.z80

@@ -9,18 +9,29 @@ lcd_ctrl        equ     0dah
 celcius_offset  equ     08ah
 pressure_offset equ     0cah
 humid_offset    equ     09eh
+spinner_offset  equ     0e7h                    ; line 4, column 20 on a 20x4 panel
+
+bs_char         equ     01h                     ; cgram slot holding our backslash
+bs_cgram        equ     048h                    ; set cgram address, slot 1 row 0
 
 bdos            equ     0005h
 conout          equ     02h
 conin           equ     01h
+dconio          equ     06h
+printstr        equ     09h
 
-char_idx        equ     10h
 
 start:
+                ld      c,printstr              ; tell the operator how to quit
+                ld      de,quitmsg
+                call    bdos
+
                 call    init_lcd
                 call    init_siob
                 call    lcd_delay
 
+                call    load_glyphs
+
                 ld      a,celcius_offset        ; write celcius label
                 out     (lcd_ctrl),a
                 call    lcd_delay
@@ -40,15 +51,23 @@ start:
                 call    print_str_to_lcd
 
 main:
-                call    read_char_b
+                call    read_char_b             ; never blocks now
+                jr      nc,check_quit           ; wire is idle, go look at the keyboard
+                ld      hl,rx_seen
+                ld      (hl),0ffh               ; note traffic, a holds the char untouched
                 call    parse_char
-                ;call    lcd_delay
+                jr      main                    ; drain the sio while it still has data
-                ;call	print_char_to_lcd
+
-                ld      c,11
+check_quit:
+                call    spin_tick               ; keep the spinner turning while idle
+                ld      c,dconio                ; direct console i/o, no echo
+                ld      e,0ffh                  ; ff polls, returning zero if no key
                 call    bdos
-                or      a
+                cp      a,051h                  ; Q
-                jr      z,main
+                ret     z
-                ret
+                cp      a,071h                  ; q
+                ret     z
+                jr      main                    ; no key, or a key we ignore
 
 init_siob:
                 ld      a,018h                  ; channel reset
@@ -83,6 +102,21 @@ init_lcd:
 
                 ret
 
+load_glyphs:                                    ; the a00 rom has yen at 5ch, so draw our own backslash
+                ld      a,bs_cgram
+                out     (lcd_ctrl),a
+                call    lcd_delay
+                ld      hl,glyph_bs
+                ld      e,08h                   ; eight rows, and e survives lcd_delay
+glyph_row:
+                ld      a,(hl)
+                out     (lcd_data),a            ; cgram address auto increments
+                call    lcd_delay
+                inc     hl
+                dec     e
+                jr      nz,glyph_row
+                ret
+
 lcd_delay:
                 ld      bc,500
 delay1:
@@ -92,17 +126,41 @@ delay1:
                 jr      nz,delay1
                 ret
 
-convert_to_hpa:
+convert_to_hpa:                                 ; shift the decimal point in (pressure) two places left
-                ld      a,(pressure)
+                ld      hl,pressure
+                ld      b,0                     ; count of digits ahead of the point
+find_point:
+                ld      a,(hl)
+                or      a
+                ret     z                       ; no point in the string, leave it alone
+                cp      a,2eh                   ; period
+                jr      z,found_point
+                inc     hl
+                inc     b
+                jr      find_point
+found_point:
+                ld      a,b
+                cp      3                       ; need three whole digits to shift by two
+                ret     c
+                dec     hl                      ; step back over the ones digit
+                dec     hl                      ; hl now holds the new tenths digit
+                ld      a,(hl)
+                ld      (hl),2eh                ; drop the point in two places left
+                inc     hl
+                ld      (hl),a                  ; and the saved digit after it
+                inc     hl
+                ld      (hl),00h                ; null terminate, discarding the rest
                 ret
 
-read_char_b:
+read_char_b:                                    ; carry set with the char in a, carry clear if nothing waiting
-wait:
                 in      a,(siob_ctrl)
                 bit     0,a
-                jr      z,wait
+                jr      z,no_char
-
                 in      a,(siob_data)
+                scf                             ; flag a as a real character
+                ret
+no_char:
+                or      a                       ; clears carry, a holds status not data
                 ret
 
 parse_char:                                     ; char should be in register a
@@ -119,20 +177,31 @@ parse_char:                                     ; char should be in register a
                 cp      a,048h                  ; H character
                 jr      z,set_char_idx_h        ; point the char_idx to the humidity buffer
 
+                push    af
+                ld      a,(char_cnt)            ; get number stored in char_cnt
+                cp      char_max                ; compare it to maximum character count
+                jr      nc,store_full           ; if no carry, the buffer is full
+                inc     a                       ; otherwise increment
+                ld      (char_cnt),a            ; and store back in char_cnt
+                pop     af
+
                 ld      bc,(char_idx)           ; get address stored in char_idx
                 ld      (bc),a                  ; deref that address and store char
                 inc     bc
                 ld      (char_idx),bc           ; store incremented address in char_idx
 
-                ;out	(lcd_data),a
 parse_char_done:
                 ret
+store_full:
+                pop     af
+                ret
 
 print_telem_to_lcd:
                 call    move_to_tempaddr
                 ld      hl,temperature
                 call    print_str_to_lcd
 
+                call    convert_to_hpa
                 call    move_to_presaddr
                 ld      hl,pressure
                 call    print_str_to_lcd
@@ -142,7 +211,6 @@ print_telem_to_lcd:
                 call    print_str_to_lcd
 
                 ld      a,1h
-                out     (0),a
                 ret
 
 null_term:                                      ; null terminate end of parsed string in memory
@@ -155,36 +223,25 @@ null_term:                                      ; null terminate end of parsed s
 set_char_idx_t:
                 ld      bc,temperature
                 ld      (char_idx),bc
+                xor     a                       ; reset char_cnt to zero
+                ld      (char_cnt),a
                 ret
 
 set_char_idx_p:
                 ld      bc,pressure
                 ld      (char_idx),bc
+                xor     a                       ; reset char_cnt to zero
+                ld      (char_cnt),a
                 ret
 
 set_char_idx_h:
                 ld      bc,humidity
                 ld      (char_idx),bc
+                xor     a                       ; reset char_cnt to zero
+                ld      (char_cnt),a
                 ret
 
 
-print_char_to_lcd:
-                cp      a,00h                   ; null byte
-                jr      z,lcd_done
-                cp      a,0dh                   ; carriage return
-                jr      z,lcd_done
-                cp      a,0ah                   ; new line
-                jr      z,lcd_done
-                cp      a,054h                  ; T character
-                call    z,move_to_tempaddr
-                cp      a,050h                  ; P character
-                call    z,move_to_presaddr
-                cp      a,048h                  ; H character
-                call    z,move_to_humidaddr
-                out     (lcd_data),a
-lcd_done:
-                ret
-
 print_str_to_lcd:                                 ; place memory address in hl first
                 ld      a,(hl)
                 or      a
@@ -197,16 +254,49 @@ print_str_to_lcd:                                 ; place memory address in hl f
 print_done:
                 ret
 
+spin_tick:                                      ; count down, then step the spinner one frame
+                ld      hl,(spin_cnt)
+                dec     hl
+                ld      (spin_cnt),hl
+                ld      a,h                     ; dec hl leaves the flags alone
+                or      l
+                ret     nz                      ; not time yet
+
+                ld      hl,spin_ticks           ; reload, so the interval stays regular
+                ld      (spin_cnt),hl
+
+                ld      a,(rx_seen)             ; did anything arrive this interval?
+                or      a
+                ret     z                       ; no, hold the frame and stop spinning
+                xor     a
+                ld      (rx_seen),a             ; clear it for the next interval
+
+                ld      a,(spin_idx)
+                inc     a
+                and     03h                     ; four frames, then wrap
+                ld      (spin_idx),a
+
+                ld      hl,spinner
+                ld      d,00h
+                ld      e,a
+                add     hl,de                   ; hl now points at the frame character
+
+                ld      a,spinner_offset
+                out     (lcd_ctrl),a            ; park the cursor bottom right
+                call    lcd_delay
+                ld      a,(hl)                  ; fetch late, lcd_delay wrecks a and bc but not hl
+                out     (lcd_data),a
+                call    lcd_delay
+                ret
+
 move_to_tempaddr:
-                ld      c,a
                 ld      a,85h
                 out     (lcd_ctrl),a
-                ld      a,c
                 call    lcd_delay
                 ret
 
 move_to_presaddr:
-                ld      a,0c1h
+                ld      a,0c3h
                 out     (lcd_ctrl),a
                 call    lcd_delay
                 ret
@@ -218,9 +308,24 @@ move_to_humidaddr:
                 ret
 
 clabel:         DB      'degree C',0
-plabel:         DB      'pascal',0
+plabel:         DB      'hPa',0
 hlabel:         DB      '% RH',0
 
+quitmsg:        DB      'Press Q to quit',0dh,0ah,'$'
+
+spinner:        DB      '-','/','|',bs_char
+glyph_bs:       DB      00h,10h,08h,04h,02h,01h,00h,00h
+spin_ticks      equ     3000                    ; idle polls per frame, tune on real hardware
+spin_idx        DB      03h                     ; wraps to the first frame on the next tick
+spin_cnt        DW      spin_ticks
+rx_seen         DB      00h                     ; set on every byte off the sio
+
+char_max        equ     15
+char_cnt        DB      0
+
+char_idx        DW      scratch
+scratch:        DS      16
+
 temperature:    DS      16
 humidity:       DS      16
 pressure:       DS      16