'SDR receiver software V1.0
'Si570-C2  1-160 MHz
'PR0032
'DL6ZB build PR003211230312

'The ATtiny25 µP uses the internal clock. The divider fuse is set "off".

$regfile = "attiny25.dat"
$crystal = 8000000

Config Sda = Portb.4
Config Scl = Portb.3

Dim Status As Byte
Dim Band As Byte

I2cinit

Config Portb.0 = Input
Portb.0 = 1
Config Portb.1 = Input
Portb.1 = 1
Config Portb.2 = Input
Portb.2 = 1

Status = 0                                                  

Do

Band = Pinb

Shift Band , Left , 5
Shift Band , Right , 5

If Band <> Status Then
   Select Case Band
      Case 7 : Gosub 20m_init
      Case 6 : Gosub 80m_init
      Case 5 : Gosub 40m_init
      Case 3 : Gosub 30m_init
   End Select
End If

Loop

80m_init:
' 80m initialized to 3524 kHz for a 48 kHz soundcard. Frequency = 48 kHz/2 > 24 kHz >> 3524 kHz

I2cstart
I2cwbyte &HAA                                               'I2C write address Si570
I2cwbyte 137
I2cwbyte &H10
I2cstop

I2cstart
I2cwbyte &HAA
I2cwbyte 7
I2cwbyte &B10101001	'These binary data sets are the divider factors for the Si570 oscillator.
I2cwbyte &B11000010	'These data sets may be different for each oscillator chip and maybe
I2cwbyte &B11000110	'calculated everytime a new Si570 is installed. The reason is that the
I2cwbyte &B10001110	'built-in crystal oscillator may differ in frequency a few Hertz. This
I2cwbyte &B10110000	'can cause a few hundred Hertz difference to that what I measured for
I2cwbyte &B00000000	'the Si570 used in my RX. See the Silicon Labs manual for more information.
I2cstop
Status = 6
Gosub Set_frequency
Return


40m_init:
' 40m, 7024 kHz

I2cstart
I2cwbyte &HAA                                               'I2C write address Si570
I2cwbyte 137
I2cwbyte &H10
I2cstop

I2cstart
I2cwbyte &HAA
I2cwbyte 7
I2cwbyte &B11100100
I2cwbyte &B00000011
I2cwbyte &B00001010
I2cwbyte &B11110100
I2cwbyte &B01010111
I2cwbyte &B10011001
I2cstop
Status = 5
Gosub Set_frequency
Return



30m_init:
' 30m, 10124 kHz

I2cstart
I2cwbyte &HAA                                               'I2C write address Si570
I2cwbyte 137
I2cwbyte &H10
I2cstop

I2cstart
I2cwbyte &HAA
I2cwbyte 7
I2cwbyte &B11100010
I2cwbyte &B10000010
I2cwbyte &B11101100
I2cwbyte &B01111101
I2cwbyte &B11000000
I2cwbyte &B01110100
I2cstop
Status = 3
Gosub Set_frequency
Return



20m_init:
' 20m, 14024 kHz

I2cstart
I2cwbyte &HAA                                               'I2C write address Si570
I2cwbyte 137
I2cwbyte &H10
I2cstop

I2cstart
I2cwbyte &HAA
I2cwbyte 7
I2cwbyte &B10100010
I2cwbyte &B01000010
I2cwbyte &B11000010
I2cwbyte &B11101101
I2cwbyte &B10011111
I2cwbyte &B00010100
I2cstop
Status = 7
Gosub Set_frequency
Return


' set frequency and start Si570 DCO

Set_frequency:

I2cstart                                                    'register 137 -new frequency-
I2cwbyte &HAA
I2cwbyte 137
I2cwbyte 0
I2cstop

I2cstart                                                    'register 125 DCO start
I2cwbyte &HAA
I2cwbyte 135
I2cwbyte &H40
I2cstop
Return