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Marcwolf
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Joined: 05/03/2022
Location: Australia
Posts: 3

Posted: 02:10am 07 Mar 2022

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Hi Folks.
Been a long while since I have been back here.

I am wondering if anyone has some code that will drive the 16 Channel Servo Controllers based on the PCA9685.

Adafruit 16 Channel Servo Controller

This is a very popular board since it runs on I2C and you can daisy chain multiple boards together.

I have been working on a 2 part project.

1. A ESP32 using the PCA9685 to control Servo's. Positions are read every 0.25 sec from a SD card and then sent to the servo. This give a resolution where a slow sweeping move can be obtained that runs over many seconds.. Not just a fast Point A to Point B movement.

2. A programmer using a PicoMite, Touch Screen, and an SD Card. This can be plugged in to a PCA9685 and the user can then use the touch screen to set the positions of the servos and record them on to the SD Card. Naming of Servo's, Min/Max, Defaults, and where the servo is reverse or not can all be included in to the code.
Afterward the CD Card can be plugged in to the ESP32 (1) and set to run.

My big issue has been trying to find a easily programmable graphics system with multiple screens. Plus I am very comfortable with using BASIC.

Can anyone help with the Servo Controller?
Many thanks
David Boccabella a.k.a. Marcwolf

Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9757

Posted: 02:36am 07 Mar 2022

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Should be easy enough, you just need to read the manual for the controller chip used, and translate that into MMBASIC instead of Arduino C code.

I'll have a look at the PDF for this chip and post back later, but as the chip is clever enough to keep the PWM rates running for all 16-channels by itself, it should simply be a case of using the chip PDF to work out the commands you need to send, and using the I2C commands - see the appendix's in the various user manuals, as there is an I2C section in each one.

Smoke makes things work. When the smoke gets out, it stops!

Tinine
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Joined: 30/03/2016
Location: United Kingdom
Posts: 1646

Posted: 03:54am 07 Mar 2022

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Any reason for not simply using a slaved Picomite? Doesn't it have 16 PWMs?

Craig

disco4now

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Joined: 18/12/2014
Location: Australia
Posts: 1052

Posted: 04:17am 07 Mar 2022

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Here something I used some time ago. Should be a start.

Quote '------------------------------------------------------------------------------'
' Micromite library for PCA9685 '
' Uses PCA9685 16-channel PWM over I2C to support 16 Servos or PWM pins '
' '
' '
' Author: Disco4now TBS Forum '
' '
dim ProgTitle$ = "PCA9685 Test Suite" '
' '
Dim ProgVer$ = "v1.0.0" '
' '
Dim ProgDate$ = "03-Apr-2018" '
'------------------------------------------------------------------------------'
'Code for a Micromite to communicate with a PCA9685 16-channel PWM over I2C.
'Also contains routine to allow calibration of servos.
'The console input is scanned and characters read as they are typed

' ServoMIN(16),ServoMAX(16) hold min and max pulse widths for 0 and 180 deg respectively.
' nominal values 800 and 2200 but adjust to suit your particular servos
' calibration values for each servo
' 0-9,a-f used to select the servo to calibrate.
' SPACEBAR sets servo near the centre i.e 90 deg for nominal range of 0-180
' right arrow sets servo to 180 deg.SPACEBAR to reurn to centre.
' PgUp/PgDn increase/decrease pulse width by 10uS. Up/Down Arrows increase/decrease by 1uS
' Press SPACEBAR and current value will print to console.
' When the servo is operating correctly then record the max/min values and used them
' to set ServoMIN(x) and ServoMAX(x) values in the PWMInit() routine.
' nominal values 800 and 2200 but adjust to suit your servos
' e.g.
' ServoMIN(0)=480:ServoMAX(0)=2140
' ServoMIN(1)=480:ServoMAX(1)=2085
' ServoMIN(2)=460:ServoMAX(2)=2125

' Once these are set you just use
' SERVOSet(id,angle)
' to set individual servo to desired angle

Option Explicit
Option Default NONE

'================================================================================================
' Data Variables
'================================================================================================

Dim integer loc0last,loc0now,loc1last,loc1now,loc2last,loc2now,GetCon=0,GetCom1=0,GetCom2=0
Dim integer i,id=0,highlow=0
'================================================================================================
' Program Initialization
'================================================================================================

Print "Starting " + ProgTitle$ + ": " + ProgVer$ + " - " + ProgDate$

settick 100,IsSerialOrConsoleComplete,1

'Initialise the PCA9685 16-channel PWM over I2C at frequency of 1000
PWMInit 50 '50Hz for 20ms pulse period represented by 4096 ticks

'Uncomment to sweep servos at start up.
' for i=0 to 15
' SERVOset i,0
' pause 500
' SERVOset i,180
' pause 500
' SERVOset i,90
' pause 500
' next i
'================================================================================================
' Main program loop
'================================================================================================

do
'Watchdog 40000 'reset after 40 secs on hang
'==============================Check Console and Serial Ports====================================
IF GetCon=1 then
ReadConsole 'If data in console1 then GOSUB GetConsole
END IF

IF GetCom1=1 then
ReadSerial1 'If data in COM1 then GOSUB GetSerial1
END IF

IF GetCom2=1 then
ReadSerial2 'If data in COM2 then GOSUB GetSerial2
END IF

Loop

'================================================================================================
' Procedures providing program functionality components
'================================================================================================
'Checks console and serial ports for data and sets flag if data has stopped coming in.
'flag triggers read of the data in the main program loop
sub IsSerialOrConsoleComplete

'Check console and set flag if data exists and has stopped coming in
loc0now=LOC(#0)
IF Loc0now>0 then
IF loc0now=loc0last THEN 'data finished
GetCon=1 'If data in CON then set GetConsole flag
else
loc0last=loc0now
ENDIF
END IF

'Check COM1 and set flag if data exists and has stopped coming in
' loc1now=LOC(#1)
' IF loc1now > 0 THEN
' if loc1now=loc1last then 'data finished
' GetCom1=1
' ELSE
' loc1last=loc1now
' ENDIF
' ENDIF
'
'Check COM2 and set flag if data exists and has stopped coming in
' loc2now=LOC(#2)
' IF loc2now > 0 THEN
' if loc2now=loc2last then 'nothin new
' GetCom2=1
' ELSE
' loc2last=loc2now
' ENDIF
' ENDIF

end sub

'Reads data from the console
SUB ReadConsole
local char$
LOCAL INTEGER i,j,k
j=LOC(#0)
char$= INPUT$(100,#0)

if char$<>"" then

If len(char$)=1 then
' ? char$;
' ? ASC(left$(char$,1));

IF Char$="0" then id=0
IF Char$="1" then id=1
IF Char$="2" then id=2
IF Char$="3" then id=3
IF Char$="4" then id=4
IF Char$="5" then id=5
IF Char$="6" then id=6
IF Char$="7" then id=7
IF Char$="8" then id=8
IF Char$="9" then id=9
IF Char$="a" then id=10
IF Char$="b" then id=11
IF Char$="c" then id=12
IF Char$="d" then id=13
IF Char$="e" then id=14
IF Char$="f" then id=15

if char$=chr$(145) then 'F1 VT100
? "F1"
end if
if char$=chr$(146) then 'Home VT100
? "F2"
end if
if char$=chr$(147) then 'Home VT100
? "F3"
end if
if char$=chr$(148) then 'Home VT100
? "F4"
end if
if char$=chr$(149) then 'F1 VT100
? "F5"
end if
if char$=chr$(150) then 'Home VT100
? "F6"
end if
if char$=chr$(151) then 'Home VT100
? "F7"
end if
if char$=chr$(152) then 'Home VT100
? "F8"
end if
if char$=chr$(153) then 'Home VT100
? "F9"
end if
if char$=chr$(155) then 'Home VT100
? "F11"
end if
if char$=chr$(156) then 'Home VT100
? "F12"
end if
if char$=chr$(127) then 'up arrow VT100
? "Del"
END IF
if char$=chr$(128) then 'up arrow VT100
'? "Up Arrow"
if highlow=0 then
ServoMIN(id)=ServoMIN(id)+1
else
ServoMAX(id)=ServoMAX(id)+1
end if

END IF
if char$=chr$(129) then 'down arrow
'? "Down Arrow"
if highlow=0 then
ServoMIN(id)=ServoMIN(id)-1
else
ServoMAX(id)=ServoMAX(id)-1
end if

END IF
if char$=chr$(131) or char$=chr$(4) then 'right arrow VT100 MMEdit
'?"Right Arrow"
SERVOSet(id ,180)
highlow=1

END IF
if char$=chr$(130) or char$=chr$(19) then 'left arrow VT100 VT100 MMEdit
'? "Left Arrow"
SERVOSet(id ,0)
highlow=0

end if
if char$=chr$(132) then
? "INS"
end if
if char$=chr$(133) then
? "133"
end if
if char$=chr$(134) then
? "Home"
end if
if char$=chr$(135) then
? "End"
end if
if char$=chr$(136) then 'PgUp VT100
If highlow=0 then
ServoMIN(id)=ServoMIN(id)+10
else
ServoMAX(id)=ServoMAX(id)+10
end if
end if
if char$=chr$(137) then 'PgUp VT100
if highlow=0 then
ServoMIN(id)=ServoMIN(id)-10
else
ServoMAX(id)=ServoMAX(id)-10
end if
end if
if char$=chr$(138) then
? "138"
end if
if char$=chr$(139) then
? "ALT"
end if
if char$=chr$(140) then
? "140"
end if
IF char$=" " THEN
' ? "SPACE BAR"
SERVOSet(id ,90)
? id,ServoMIN(id),ServoMAX(id);
If highlow=1 then
? " High(180)"
else
? " Low(0)"
ENDIF

endif
else
? char$;
? ASC(left$(char$,1));
endif
IF ASC(Left$(char$,1))=27 then
? "ESC"
end if

end if
End if

End sub

'================================================================================================
' PCA9685 I2C PWM Routines
'================================================================================================
'Code for a Micromite to communicate with a PCA9685 16-channel PWM over I2C.
'Original Author:- Limor Fried/Ladyada for Adafruit Industries
'Ported to MMBasic by Disco4now!, TBS forums
'**********************************************************************************
' This is a library for our Adafruit 16-channel PWM & Servo driver
' Pick one up today in the adafruit shop!
' ------> http://www.adafruit.com/products/815
' These displays use I2C to communicate, 2 pins are required to
' interface. For Arduino UNOs, thats SCL -> Analog 5, SDA -> Analog 4
' Adafruit invests time and resources providing this open source code,
' please support Adafruit and open-source hardware by purchasing
' products from Adafruit!
' Written by Limor Fried/Ladyada for Adafruit Industries.
' BSD license, all text above must be included in any redistribution
'**********************************************************************************

SUB SERVOSet(id as integer,angle as integer)
'set individual servo to desired angle
local integer tickoff
tickoff=4096*(ServoMin(id)+(ServoMAX(id)-ServoMIN(id))*angle/180)/20000
'? tickoff
PWMSet(id ,1,tickoff)
end sub

SUB PWMSetPin(id as integer,value as integer,inv as integer)
'Helper to set pin PWM output. Sets pin without having to deal with on/off tick placement
'and properly handles a zero value as completely off and 4095 as completely on.
'Optional invert parameter supports inverting the pulse for sinking to ground.
'id is PWM output pin, from 0 to 15
'value is the number of ticks out of 4096 to be active, should be a value from 0 to 4095 inclusive.
'inv if true, inverts the output, defaults to 'false'

'clamp value between 0 and 4095 inclusive.
if value > 4095 then value=4095
if value < 0 then value=0

if inv=0 then
if value=0 then
'special value for fully off
PWMSet(id ,4096,0)
else if value=4095 then
'special value for fully on
PWMSet(id ,0,4096)
else
PWMSet(id, 0, 4095-value);
endif
else
if value=4095 then
PWMSet(id ,4096,0)
else if value=0 then
PWMSet(id ,0,4096)
else
PWMSet(id, 0, value);
endif
endif

end sub

SUB PWMSet(id as integer,ontick as integer,offtick as integer)
'main routine -sets the PWM output of one of the PCA9685 pins
' id - One of the PWM output pins, from 0 to 15
' ontick - At what point in the 4096-part cycle to turn the PWM output ON
' offtick - At what point in the 4096-part cycle to turn the PWM output OFF
i2c write PCA9685_ADDRESS,0,5,LED0_ON_L+4*id,ontick and &HFF,ontick >> 8 ,offtick AND &HFF ,offtick >> 8

IF MM.I2C then ERROR "slave did not respond in PWMset"
END SUB

SUB PWMInit(freq as FLOAT)
'Select one of the following possible PCA9685 I2C Addresses in range 40-7F
'40 is default for no links on A5-A0 address pins.
'Call once at the start of the program with desired frequency to be used on all pins

dim integer PCA9685_ADDRESS = &H40 'default &H40 (&H40-&H7F)
DIM INTEGER PCA9685_MODE1=&H0
DIM INTEGER PCA9685_PRESCALE=&HFE
DIM INTEGER LED0_ON_L=&H6
DIM INTEGER LED0_ON_H=&H7
DIM INTEGER LED0_OFF_L=&H8
DIM INTEGER LED0_OFF_H=&H9

DIM INTEGER ServoMIN(16),ServoMAX(16)
'calibration values for each servo
' nominal values 800 and 2200 but adjust to suit your servos
ServoMIN(0)=480:ServoMAX(0)=2140
ServoMIN(1)=480:ServoMAX(1)=2085
ServoMIN(2)=460:ServoMAX(2)=2125
ServoMIN(3)=475:ServoMAX(3)=2050
ServoMIN(4)=480:ServoMAX(4)=2160
ServoMIN(5)=480:ServoMAX(5)=2160
ServoMIN(6)=480:ServoMAX(6)=2160
ServoMIN(7)=480:ServoMAX(7)=2160
ServoMIN(8)=480:ServoMAX(8)=2160
ServoMIN(9)=480:ServoMAX(9)=2160
ServoMIN(10)=480:ServoMAX(10)=2160
ServoMIN(11)=480:ServoMAX(11)=2160
ServoMIN(12)=480:ServoMAX(12)=2160
ServoMIN(13)=480:ServoMAX(13)=2160
ServoMIN(14)=480:ServoMAX(14)=2160
ServoMIN(15)=480:ServoMAX(15)=2160

i2c open 10, 100

'reset the PCA9685 to power on state
i2c write 0,0,1, &H06
IF MM.I2C then ERROR "slave did not respond at power eset"
PAUSE 1

'reset the PCA9685
i2c write PCA9685_ADDRESS,0,2,PCA9685_MODE1, &H80
IF MM.I2C then ERROR "slave did not respond at reset"
PAUSE 1
'set pwm frequency
if freq=0 then freq=1000 ' set a default if not set.
PWMSetFreq(freq)
END SUB

SUB PWMSetFreq(freq as FLOAT)
'sets or changes PWM frequency.
'freq range 40-1000 hz
local integer mode1,GetData(1)
dim float prescaleval = 25000000/4096
dim integer prescale,currentmode
freq=freq * 0.9 ' Correct for overshoot in the frequency setting
prescale=INT((prescaleval/freq)-0.5)
i2c write PCA9685_ADDRESS, 0, 1, PCA9685_MODE1
i2c read PCA9685_ADDRESS, 0, 1, mode1 ' read current mode
IF MM.I2C then ERROR "slave did not respond 2"
i2c WRITE PCA9685_ADDRESS, 0, 2,PCA9685_MODE1, mode1 OR &H10 ' set sleep bit so change of scaler allowed
i2c WRITE PCA9685_ADDRESS, 0, 2,PCA9685_PRESCALE,prescale 'set the prescaler
i2c read PCA9685_ADDRESS, 0, 1, GetData() ' read prescaler
IF MM.I2C then ERROR "slave did not respond 3"
i2c WRITE PCA9685_ADDRESS, 0, 2, PCA9685_MODE1,mode1
pause 1
i2c WRITE PCA9685_ADDRESS, 0, 2, PCA9685_MODE1,mode1 OR &HA0 'This sets the MODE1 register to turn on auto increment.
END SUB

F4 H7 FotS F4xGT

Marcwolf
Newbie

Joined: 05/03/2022
Location: Australia
Posts: 3

Posted: 12:39pm 07 Mar 2022

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DiscoNow:- WOW.. Many many thanks . This will certainly give me something to work the BASIC's from - No pun intented.

Tinine :- Te reason for not using the PicoMite to drive the servos is that the PCA9685 is NOT limited to just 16 servos. It can be daisy chained and run over 500 servos.

Again many thanks for everyone's help.

Tinine
Guru

Joined: 30/03/2016
Location: United Kingdom
Posts: 1646

Posted: 04:11pm 07 Mar 2022

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Marcwolf said DiscoNow:- WOW.. Many many thanks . This will certainly give me something to work the BASIC's from - No pun intented.

Tinine :- Te reason for not using the PicoMite to drive the servos is that the PCA9685 is NOT limited to just 16 servos. It can be daisy chained and run over 500 servos.

Again many thanks for everyone's help.

but nothing to stop PicoMites being chained together.

I have 255 addresses on my RS422/485 full duplex link which could give me 255*16 servos.

Craig

Tinine
Guru

Joined: 30/03/2016
Location: United Kingdom
Posts: 1646

Posted: 07:31pm 07 Mar 2022

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@Marcwolf

Sounds like you have something cool going on

I use PicoMites for system management and I/O expansion BUT the heavy lifting (real-time) stuff is handled by the Parallax P2 "Edge" module.

The P2 can give you at least 56 channels of PWM and even without over clocking, you are looking at 14bit resolution @10KHz.

This would give you the best synchronisation and coordination possible.
Programming in "FlexBasic" is a walk in the park.

EIGHT parallel processors and not as scary as it sounds

Craig

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