StarTracker for DE10-Nano Board.

One device to control and track a equatorial mount. I use it with Skywatcher EQ5 with two NEMA 17 2A 200 step motors, two DRV8825, two 12--teeth timing pully, two 60-teeth timing pully and two 152mm timing belts. It was controlled from the Ekos telescope ecosystem with indi_eqmod_telescope and indi_nikon_ccd running on the ARM core.

DE10-nano has one USB OTG. I connected it to a usb hub and then to the nikon camera and a wifi dongle.

Hardware Design

RA/DE DRV8825 controller

The two motors are controlled by ip/drv8825.vhd which can accept backlash offsets, slew tracking (continuous motor operation at a given period) and goto commands which can either be based on a targeted step count or an increment or decrement count.

The steps are counted at 50 Mhz; depending of the voltage on the motor the minimum period would change. at 20 v, the minim period is 125 ticks.

The goto commands can contain acceleration flag which will accelerate the motor to the targetted speed over a period of 2 seconds. The flag is ignored by the design if the number of increment/decrement needed for the operation is not high enough to justify their use; or is the period is not short enough to justify it.

Ports	Description
clk_50	clock; must be 50 MHz
rstn_50	Active low reset
drv8825_enable_n	pin to DRV8825 enable pin (active low). Pin is only enabled when motors are spinning
drv8825_mode [2 downto 0]	DRV8825 mode selector, set from the command mode. When it is set as 5 or higher, the step counter is incremented by one. When it is 4, than by 2; 3 -> 4; 2 -> 8; 1 -> 16; 0 -> 32 in order to keep with the microsteppings.
drv8825_sleep_n drv8825_rst_n	to the DRV8825
drv8825_step	Clock for the DRV8825
drv8825_direction	direction of the DRV8825
drv8825_fault_n	reporting fault on DRV8825
ctrl_step_count [32 downoto 0]	reports the current step count to the top level
ctrl_status [31 downto 0]	reports status update to the top level, e.g. is the motor running, what mode, etc.
ctrl_cmdcontrol [0]	Goto command parameters. This is the execute pin. Command is only executed at the rising edge of this bit
ctrl_cmdcontrol [1]	Defines goto command parameter. When high, the command is interpretted as a goto call, i.e. motor will spin until that counter reaches the value defined by ctrl_cmdduration. When low, the command is interpreted as a simple increment or decrement command, where the motor is spun for the number of cycles defined by ctrl_cmdduration.
ctrl_cmdcontrol [2]	Defines goto command parameter related to the director of the motor
ctrl_cmdcontrol [3]	Defines park command parameter. motor will spin till counter reaches zero
ctrl_cmdcontrol [6 downto 4]	Defines goto command parameter related to the direction of the motor.
ctrl_cmdcontrol [7]	Defines goto command parameter related acceleration of the motor. When high, acceleration and de-acceleration ramps are to be used.
ctrl_cmdcontrol [30]	When high, it cancels the current any command currently being processed immediately.
ctrl_cmdcontrol [31]	When high, it cancels the current any command currently being processed whilst deaccelating.
ctrl_cmdtick [31 downto 0]	Define goto parameters related to the period at which command is to be executed in.
ctrl_cmdduration [31 downto 0]	Define goto parameters related to the number of cycles/target count of the command.
ctrl_backlash_tick [2 downto 0]	Define backlash parameters related the motor mode.
ctrl_backlash_tick [31 downto 3]	Define backlash parameters related to the steps or the number of ticks the backlash correction is to execute in. Backlash is active when it is a non-zero value.
ctrl_backlash_duration [31 downto 0]	Define backlash parameters related to the steps the backlash correction is to execute for. Backlash is active when it is a non-zero value.
ctrl_counter_load [31 downto 0]	Overwrites the current step count; count is updated on the rising edge of bit 31. Therefore 31 bits are available for a possible max count.
ctrl_counter_max [31 downto 0]	Loads the maximum count per revolution; count is updated on the rising edge of bit 31. Therefore 31 bits are available for a possible max count.
ctrl_trackctrl [0]	Define slew to/tracking parameters. Only executed when no goto command is being executed. Bit 0 must be high if tracking is to be enabled.
ctrl_trackctrl [1]	Define slew to/tracking parameters. Bit 1 defines the direction of motion
ctrl_trackctrl [5 downto 2]	Define slew to/tracking parameters. Bit 2-5 defines the motor mode
ctrl_trackctrl [31 downto 6]	Define slew to/tracking parameters. remaining bits defines the speed/period is number of 20 ns ticks.

The following shows the pinmap on the board:

GPIO_0(1) <= ra_enable_n; -- pin 2
GPIO_0(3) <= ra_mode(0); -- pin 4
GPIO_0(5) <= ra_mode(1); -- pin 6
GPIO_0(7) <= ra_mode(2); -- pin 8
GPIO_0(9) <= ra_rst_n; -- pin 10
GPIO_0(8) <= ra_sleep_n; -- pin 9
GPIO_0(11) <= ra_step; -- pin 14
GPIO_0(13) <= ra_direction;-- pin 16
GPIO_0(17) <= de_enable_n;-- pin 20
GPIO_0(19) <= de_mode(0); -- pin 22
GPIO_0(21) <= de_mode(1); -- pin 24
GPIO_0(23) <= de_mode(2); -- pin 26
GPIO_0(25) <= de_rst_n; -- pin 28
GPIO_0(24) <= de_sleep_n; -- pin 27
GPIO_0(27) <= de_step; -- pin 32
GPIO_0(29) <= de_direction;-- pin 34

Top Level

The two ips are controllerd from the ARM core. The Avalon MM bus is passed through two altera_up_avalon_to_external_bus_bridge, one for status and one for control. The are mapped onto the registers which feed the two ips.

Camera Triggers

To facilitate the use of older cameras which cannot be triggered in bulb mode over the usb, there are two gpios which are used to send triggers. they can be passed to an optoisolator to connect to the camera remote trigger ports.

   GPIO_0(35) <= camera_trigger(0); -- pin 40
   GPIO_0(34) <= camera_trigger(1); -- pin 39

Polar LED

A 8 bit std_logic_vector can be set to a value which is used to generate a PWM signal in order to connect to an LED to be used as a polar illuminator

LED Status

DE10-NANO has 8 leds which are used to show the status of the device. There are four state of operation

1. during startup, the first led will be flashing whilst all the other leds will be on solid. This indicates that the linux software is yet to start.
2. upon the start of the linux software, the led will display the IP address of the device. This is the default state when the motors are not spinning
3. if ethernet fails to set up a link. all leds will blink in sync indicating a communication fault.
4. when motors are spinning, -> a. led_status(0) -> RA motor active b. led_status(1) <= RA motor direction; c. led_status(2) <= RA motor has valid signals; d. led_status(3) <= the 9th bit of the RA current count; a. led_status(4) -> DE motor active b. led_status(5) <= DE motor direction; c. led_status(6) <= DE motor has valid signals; d. led_status(7) <= the 9th bit of the DE current count;

Software design

The software uses koheron-server to commincate with a client over the ethernet/wifi. look here: https://github.com/rsarwar87/de10-sky-tracker/blob/master/koheron-server/README.md

Register Map

The stutus and the control altera_up_avalon_to_external_bus_bridges. The offsets for these are 0xFF250000 and 0xFF260000.

Status

The following are the status registers in the

Ports	Offset w.r.t. 0xFF250000	size	Description
dna	0x0	64-bit word	Returns fixed value, design ID
step_count[0]	0x8	32-bit word	Current RA step count
step_count[1]	0xC	32-bit word	Current DE step count
status[0]	0x10	32-bit word	Current RA status
status[1]	0x14	32-bit word	Current DE status
forty_two	0x18	32-bit word	always returns 42, to check if device is working properly

Control

The following are the status registers in the

Ports	Offset w.r.t. 0xFF260000	size	Description
counter_load[0]	0x0	32-bit word	RA load counter
counter_load[1]	0x4	32-bit word	DE load counter
counter_max[0]	0x8	32-bit word	RA max count
counter_max[1]	0xC	32-bit word	DE max count
cmdcontrol[0]	0x10	32-bit word	RA Command control
cmdcontrol[1]	0x14	32-bit word	DE Command control
cmdduration[0]	0x18	32-bit word	RA Command duration
cmdduration[1]	0x1C	32-bit word	DE Command duration
trackctrl[0]	0x20	32-bit word	RA tracking control
trackctrl[1]	0x24	32-bit word	DE tracking control
cmdtick[0]	0x28	32-bit word	RA Command period
cmdtick[1]	0x2C	32-bit word	DE Command period
backlash_tick[0]	0x30	32-bit word	RA Backlash period
backlash_tick[1]	0x34	32-bit word	DE Backlash period
backlash_duration[0]	0x38	32-bit word	RA Backlash duration
backlash_duration[1]	0x3c	32-bit word	DE Backlash duration
led	0x40	32-bit word	IP address of the device
led_pwm	0x44	32-bit word	Polar LED
camera_trigger	0x48	32-bit word	Current RA status

Linux rootfs:

this repo tells how to make the 5.4 kernel and subsequent rootfs https://github.com/rsarwar87/altera-soc-rootfs

Installing server on the ARM

Clone the repo on the DE10 running linux.

cd 
git clone https://github.com/rsarwar87/de10-sky-tracker --depth=1
cd de10-sky-tracker/koheron-server
make server
mkdir build
cd build
cmake ../
make
sudo cp serverd /usr/local/bin/.

Create a file in /etc/systemd/system/koheron-server.service and fill it with:

[Unit]
Description=Koheron TCP/Websocket server
After=network.target unzip-default-instrument.service
[Service]
Type=notify
NotifyAccess=all
ExecStart=/use/local/bin/serverd
ExecStop=/usr/bin/pkill -SIGINT serverd
KillSignal=SIGKILL
# No limitation in the number of restarts per time interval
StartLimitInterval=0
[Install]
WantedBy=multi-user.target

Finally run:

systemctl enable koheron-server.service
systemctl start koheron-server.service

Indilib software stack on the ARM

You only need to do this is you wish to run indiserver on the DE10-nano, either because it can, or because you need to use the camera triggers or because you wish to connect to the camera using the DE10 USB OTG.

First install the full repo of indi-lib

cd 
sudo apt-get install -y libnova-dev libcfitsio-dev libusb-1.0-0-dev zlib1g-dev libgsl-dev build-essential cmake git libjpeg-dev libcurl4-gnutls-dev libtiff-dev libfftw3-dev
git clone --depth 1 https://github.com/indilib/indi.git
cd  indi
mkdir build
cmake -DCMAKE_INSTALL_PREFIX=/usr ../
make -j4
sudo make install

The device needs some modified indi-3rd party drivers as well to enable controlling the mount and the camera triggers on the FPGA.

cd 
git clone https://github.com/rsarwar87/de10-sky-tracker --depth=1
cd de10-sky-tracker/koheron-server/
make server
cd libclient
mkdir build
cd build
cmake ../ -DCMAKE_INSTALL_PREFIX=/usr ../
make
sudo make install

On the device:

sudo apt-get install libnova-dev libcfitsio-dev libusb-1.0-0-dev zlib1g-dev libgsl-dev build-essential cmake git libjpeg-dev libcurl4-gnutls-dev libtiff-dev libftdi-dev libgps-dev libraw-dev libdc1394-22-dev libgphoto2-dev libboost-dev libboost-regex-dev librtlsdr-dev liblimesuite-dev libftdi1-dev
cd
git clone https://github.com/rsarwar87/indi-3rdparty --depth=1
cd indi-3rdparty/indi-eqmod
mkdir build
cd  build
cmake -DCMAKE_INSTALL_PREFIX=/usr ../
make
sudo make install
cd 
cd indi-3rdparty/indi-gphoto
mkdir build
cd build
cmake -DCMAKE_INSTALL_PREFIX=/usr ../
make
sudo make install

To run the device, connect everything and then from the terminal:

export SKY_IP="127.0.0.1"
indiserver indi_nikon_ccd indi_eqmod_telescope

Installing/configuring EKOS linux binaries on laptop.

Installation:

sudo apt-add-repository ppa:mutlaqja/ppa
sudo apt-get update
sudo apt-get install indi-full kstars-bleeding

Custom driver if indiserver is to run locally on the laptop/PC.

sudo apt-get install libnova-dev libcfitsio-dev libusb-1.0-0-dev zlib1g-dev libgsl-dev build-essential cmake git libjpeg-dev libcurl4-gnutls-dev libtiff-dev libftdi-dev libgps-dev libraw-dev libdc1394-22-dev libgphoto2-dev libboost-dev libboost-regex-dev librtlsdr-dev liblimesuite-dev libftdi1-dev
cd
git clone https://github.com/rsarwar87/indi-3rdparty --depth=1
cd indi-3rdparty/indi-eqmod
mkdir build
cd  build
make
sudo make install
cd 
## Do this if you wish to use the camera triggers only, otherwise not needed
cd indi-3rdparty/indi-gphoto
mkdir build
cd build
cmake ../
sudo make install

Running

export SKY_IP="192.168.1.122" # only if you are runing indiserver locally and not on the DE10_nano -- update ip as appropiate
kstars

after first connect make the following changes:

1. EQ mod - change device port from /dev/ttyUSB0 to /dev/ttyS0. -- this is irralevent to out system, but it is just to stop indiserver from complaining
2. If you wish to use the FPGA to trigger the camera, in the nikon camera setting, set port to "KFPGA"

Reference design:

OEM supplied LXDE GHRD.

the top level was is implemented in VHDL. The remaining ip/soc_system was taken from SoC_FB example.