Analog circuit
Yes, code of my prototipe board is very simple for now.... i use a basic compiler and a 16F876;
Device 16F876
Declare XTAL 20
DECLARE LCD_TYPE 1
DECLARE LCD_DTPORT PORTC
DECLARE LCD_CS2PIN PORTB.1
DECLARE LCD_CS1PIN PORTB.0
DECLARE LCD_RSPIN PORTB.3
DECLARE LCD_RWPIN PORTB.2
DECLARE LCD_ENPIN PORTB.4
DECLARE INTERNAL_FONT 1
DECLARE ADIN_RES 10 ' 10-bit result required
DECLARE ADIN_TAD FRC ' RC OSC chosen
DECLARE ADIN_STIME 13989 ' sample time for a windowing 50Hz filter
TRISA = %00000001 ' Configure AN0 (PORTA.0) as an input
ADCON1 = %10000000 ' Set analogue input on PORTA.0
DIM VAR1 as WORD
DIM VAR2 as WORD
DIM VARD as BYTE
DIM FREQ as BYTE
DIM XPOS as BYTE
DIM XNEW as BYTE
DIM XOLD as BYTE
DIM XDIF as BYTE
XNEW = 0
CLS
PRINT AT 4,6, "Biomonitor"
DELAYMS 1000 ' Wait for PICmicro to stabilise
CLS
LOOP:
FOR XPOS = 0 TO 127 STEP 1
VAR1 = ADIN 0 ' Place the conversion into variable VAR1
VAR1 = VAR1/200
LINE 0, XPOS, 0, XPOS, 63
LINE 1, XPOS-1, -VAR2, XPOS, -VAR1
IF VAR1 > VAR2 THEN VARD = VAR1-VAR2 : ELSEIF VARD > 4 THEN XOLD = XNEW : XNEW = XPOS : SOUND PORTB.5, [127,1]
IF XNEW > XOLD THEN XDIF = XNEW - XOLD : ELSEIF XDIF > 25 THEN FREQ = 2980 / XDIF : PRINT AT 0,20, INVERSE 0, "*" 'caracter * is modifield to a heart icon
PRINT AT 0,17, DEC FREQ
VAR2 = VAR1
NEXT
GOTO LOOP
FONT:- CData $00,$00,$00,$00,$00,$00 'Graphic character 0
CData $FF,$FF,$FF,$FF,$FF,$FF 'Graphic character 1
CData $07,$07,$07,$00,$00,$00 'Graphic character 2
CData $00,$00,$00,$07,$07,$07 'Graphic character 3
CData $E0,$E0,$E0,$00,$00,$00 'Graphic character 4
CData $00,$00,$00,$E0,$E0,$E0 'Graphic character 5
CData $FF,$FF,$FF,$00,$00,$00 'Graphic character 6
CData $00,$00,$00,$FF,$FF,$FF 'Graphic character 7
CData $07,$07,$07,$07,$07,$07 'Graphic character 8
CData $E0,$E0,$E0,$E0,$E0,$E0 'Graphic character 9
CData $E0,$E0,$E0,$07,$07,$07 'Graphic character 10
CData $07,$07,$07,$E0,$E0,$E0 'Graphic character 11
CData $FF,$FF,$FF,$E0,$E0,$E0 'Graphic character 12
CData $E0,$E0,$E0,$FF,$FF,$FF 'Graphic character 13
CData $07,$07,$07,$FF,$FF,$FF 'Graphic character 14
CData $FF,$FF,$FF,$07,$07,$07 'Graphic character 15
CData $55,$AA,$55,$AA,$55,$AA 'Graphic character 16
CData $AA,$55,$AA,$55,$AA,$55 'Graphic character 17
CData $01,$01,$01,$01,$01,$01 'Graphic character 18
CData $80,$80,$80,$80,$80,$80 'Graphic character 19
CData $FF,$00,$00,$00,$00,$00 'Graphic character 20
CData $00,$00,$00,$00,$00,$FF 'Graphic character 21
CData $FF,$01,$01,$01,$01,$01 'Graphic character 22
CData $01,$01,$01,$01,$01,$FF 'Graphic character 23
CData $FF,$80,$80,$80,$80,$80 'Graphic character 24
CData $80,$80,$80,$80,$80,$FF 'Graphic character 25
CData $00,$00,$00,$00,$00,$00 'User defined character 26
CData $00,$00,$00,$00,$00,$00 'User defined character 27
CData $00,$00,$00,$00,$00,$00 'User defined character 28
CData $00,$00,$00,$00,$00,$00 'User defined character 29
CData $00,$00,$00,$00,$00,$00 'User defined character 30
CData $00,$00,$00,$00,$00,$00 'User defined character 31
CData $00,$00,$00,$00,$00,$00 'User defined character 32
CData $00,$00,$4F,$00,$00,$00 '33 - ! - 21
CData $00,$07,$00,$07,$00,$00 '34 - " - 22
CData $14,$7F,$14,$7F,$14,$00 '35 - # - 23
CData $24,$2A,$7F,$2A,$12,$00 '36 - $ - 24
CData $23,$13,$08,$64,$62,$00 '37 - % - 25
CData $36,$49,$55,$22,$50,$00 '38 - & - 26
CData $00,$05,$03,$00,$00,$00 '39 - ' - 27
CData $1C,$22,$41,$00,$00,$00 '40 - ( - 28
CData $00,$00,$41,$22,$1C,$00 '41 - ) - 29
CData $0E,$1E,$7C,$7C,$1E,$0E '42 - * - 2A
CData $08,$08,$3E,$08,$08,$00 '43 - + - 2B
CData $00,$50,$30,$00,$00,$00 '44 - , - 2C
CData $08,$08,$08,$08,$08,$00 '45 - - - 2D
CData $00,$60,$60,$00,$00,$00 '46 - . - 2E
CData $20,$10,$08,$04,$02,$00 '47 - / - 2F
CData $3E,$51,$49,$45,$3E,$00 '48 - 0 - 30
CData $00,$42,$7F,$40,$00,$00 '49 - 1 - 31
CData $42,$61,$51,$49,$46,$00 '50 - 2 - 32
CData $21,$41,$45,$4B,$31,$00 '51 - 3 - 33
CData $18,$14,$12,$7F,$10,$00 '52 - 4 - 34
CData $27,$45,$45,$45,$39,$00 '53 - 5 - 35
CData $3C,$4A,$49,$49,$30,$00 '54 - 6 - 36
CData $01,$71,$09,$05,$03,$00 '55 - 7 - 37
CData $36,$49,$49,$49,$36,$00 '56 - 8 - 38
CData $06,$49,$49,$49,$3E,$00 '57 - 9 - 39
CData $00,$36,$36,$00,$00,$00 '58 - : - 3A
CData $00,$56,$36,$00,$00,$00 '59 - ; - 3B
CData $08,$14,$22,$41,$00,$00 '60 - < - 3C
CData $14,$14,$14,$14,$14,$00 '61 - = - 3D
CData $00,$41,$22,$14,$08,$00 '62 - > - 3E
CData $02,$01,$51,$09,$06,$00 '63 - ? - 3F
CData $32,$49,$79,$41,$3E,$00 '64 - @ - 40
CData $7E,$11,$11,$11,$7E,$00 '65 - A - 41
CData $7F,$49,$49,$49,$36,$00 '66 - B - 42
CData $3E,$41,$41,$41,$22,$00 '67 - C - 43
CData $7F,$41,$41,$22,$1C,$00 '68 - D - 44
CData $7F,$49,$49,$49,$41,$00 '69 - E - 45
CData $7F,$09,$09,$09,$01,$00 '70 - F - 46
CData $3E,$41,$49,$49,$7A,$00 '71 - G - 47
CData $7F,$08,$08,$08,$7F,$00 '72 - H - 48
CData $00,$41,$7F,$41,$00,$00 '73 - I - 49
CData $20,$40,$41,$3F,$01,$00 '74 - J - 4A
CData $7F,$08,$14,$22,$41,$00 '75 - K - 4B
CData $7F,$40,$40,$40,$40,$00 '76 - L - 4C
CData $7F,$02,$0C,$02,$7F,$00 '77 - M - 4D
CData $7F,$04,$08,$10,$7F,$00 '78 - N - 4E
CData $3E,$41,$41,$41,$3E,$00 '79 - O - 4F
CData $7F,$09,$09,$09,$06,$00 '80 - P - 50
CData $3E,$41,$51,$21,$5E,$00 '81 - Q - 51
CData $7F,$09,$19,$29,$46,$00 '82 - R - 52
CData $46,$49,$49,$49,$31,$00 '83 - S - 53
CData $01,$01,$7F,$01,$01,$00 '84 - T - 54
CData $3F,$40,$40,$40,$3F,$00 '85 - U - 55
CData $1F,$20,$40,$20,$1F,$00 '86 - V - 56
CData $3F,$40,$38,$40,$3F,$00 '87 - W - 57
CData $63,$14,$08,$14,$63,$00 '88 - X - 58
CData $07,$08,$70,$08,$07,$00 '89 - Y - 59
CData $61,$51,$49,$45,$43,$00 '90 - Z - 5A
CData $7F,$41,$41,$00,$00,$00 '91 - [ - 5B
CData $02,$04,$08,$10,$20,$00 '92 - \ - 5C
CData $00,$00,$41,$41,$7F,$00 '93 - ] - 5D
CData $04,$02,$01,$02,$04,$00 '94 - ^ - 5E
CData $40,$40,$40,$40,$40,$00 '95 - _ - 5F
CData $00,$01,$02,$04,$00,$00 '96 - ` - 60
CData $20,$54,$54,$54,$78,$00 '97 - a - 61
CData $7F,$48,$44,$44,$38,$00 '98 - b - 62
CData $38,$44,$44,$44,$20,$00 '99 - c - 63
CData $38,$44,$44,$48,$7F,$00 '100 d - 64
CData $38,$54,$54,$54,$18,$00 '101 e - 65
CData $08,$7E,$09,$01,$02,$00 '102 f - 66
CData $0C,$52,$52,$52,$3E,$00 '103 g - 67
CData $7F,$08,$04,$04,$78,$00 '104 h - 68
CData $00,$44,$7D,$40,$00,$00 '105 i - 69
CData $00,$20,$40,$44,$3D,$00 '106 j - 6A
CData $7F,$10,$28,$44,$00,$00 '107 k - 6B
CData $00,$41,$7F,$40,$00,$00 '108 l - 6C
CData $7C,$04,$18,$04,$78,$00 '109 m - 6D
CData $7C,$08,$04,$04,$78,$00 '110 n - 6E
CData $38,$44,$44,$44,$38,$00 '111 o - 6F
CData $7C,$14,$14,$14,$08,$00 '112 p - 70
CData $08,$14,$14,$18,$7C,$00 '113 q - 71
CData $7C,$08,$04,$04,$08,$00 '114 r - 72
CData $48,$54,$54,$54,$20,$00 '115 s - 73
CData $04,$3F,$44,$40,$20,$00 '116 t - 74
CData $3C,$40,$40,$20,$7C,$00 '117 u - 75
CData $1C,$20,$40,$20,$1C,$00 '118 v - 76
CData $3C,$40,$30,$40,$3C,$00 '119 w - 77
CData $44,$28,$10,$28,$44,$00 '120 x - 78
CData $0C,$50,$50,$50,$3C,$00 '121 y - 79
CData $44,$64,$54,$4C,$44,$00 '122 z - 7A
CData $08,$36,$41,$00,$00,$00 '123 { - 7B
CData $00,$00,$7F,$00,$00,$00 '124 | - 7C
CData $00,$00,$41,$36,$08,$00 '125 } - 7D
CData $00,$08,$04,$08,$04,$00 '126 ~ - 7E
Added after 16 minutes:
This is the amplifier, simplified design with minimal number of parts, single op-amp right leg drive, high common mode rejection ratio (>120dB), 0,3Hz high pass filter (remove electrodes noise) and low pass filter 108Hz (for electromiogram noise).