Hello,
If I understand correctly, the software is working.
Lets try something.
You will still need the terminal program for this test.
The test will use servo 1 and servo 3
Try the code below and let me know what the Servos are doing and if the terminal program displays:
********************
* No ACK from SD20 *
********************
Greetings,
Drifter2006

Code:
'**************** I/O PORTS ****************'
define sda port[7]
define scl port[8]
'*******************************************'
'**************** A/D PORTS ****************'

'*******************************************'
'**************** D/A PORTS ****************'

'*******************************************'
'**************** VARIABLES ****************'
define control_flags byte[1]
define i2c_nack bit[1]
define i2c_last bit[2]
define i2c_nack_count byte[2]
define i2c_byte byte[3]
define i2c_out_bit bit[24]
define i2c_in_bit bit[17]
define i2c_loop byte[4]

define servo_number byte[5]
define servo_position byte[6]
'*******************************************'
'**************** CONSTANTS ****************'
define sd20_i2c_address 194
'*******************************************'
'****************** SETUP ******************'

'*******************************************'
'***************** PROGRAM *****************'
#start
servo_number = 1
servo_position = 255
gosub sd20_servo_driver

servo_number = 3
servo_position = 255
gosub sd20_servo_driver

servo_number = 1
servo_position = 1
gosub sd20_servo_driver

servo_number = 3
servo_position = 1
gosub sd20_servo_driver

goto start
'*******************************************'
'*************** SUBROUTINES ***************'
#sd20_servo_driver
gosub start_i2c
i2c_byte = sd20_i2c_address : gosub write_byte_i2c
i2c_byte = servo_number : gosub write_byte_i2c
i2c_byte = servo_position : gosub write_byte_i2c
gosub stop_i2c
if i2c_nack_count > 9 then goto no_ack_from_sd20
if i2c_nack then goto sd20_servo_driver
return

#start_i2c
sda = 0 : scl = 0
return

#stop_i2c
sda = 0 : deact scl : deact sda
return

#write_byte_i2c
for i2c_loop = 1 to 8
sda = i2c_out_bit
deact scl
#write_byte_i2c_clock_stretch
if not scl then goto write_byte_i2c_clock_stretch
scl = 0
i2c_byte = i2c_byte shl 1
next
deact sda
deact scl
#write_byte_i2c_ack_clock_stretch
if not scl then goto write_byte_i2c_ack_clock_stretch
i2c_nack = sda
scl = 0
if i2c_nack then goto i2c_error
i2c_nack_count = 0
return
#i2c_error
i2c_nack_count = i2c_nack_count + 1
goto stop_i2c

#read_byte_i2c
i2c_last = 0
#get_i2c_byte
deact sda
for i2c_loop = 1 to 8
deact scl
#read_byte_i2c_clock_stretch
if not scl then goto read_byte_i2c_clock_stretch
i2c_in_bit = sda
scl = 0
if i2c_loop < 8 then i2c_byte = i2c_byte shl 1
next
if i2c_last then deact sda else sda = 0
deact scl
#read_byte_i2c_ack_clock_stretch
if not scl then goto read_byte_i2c_ack_clock_stretch
scl = 0
return

#read_last_byte_i2c
i2c_last = 1
goto get_i2c_byte
'*******************************************'
'******* INITIALIZATION SUBROUTINES ********'

'*******************************************'
'********* CALIBRATION SUBROUTINES *********'

'*******************************************'
'****************** DATA *******************'

'*******************************************'
'************* ERROR MESSAGES **************'
#no_ack_from_sd20
print"********************"
print"* No ACK from SD20 *"
print"********************"
pause 50
return
'*******************************************'