The IPEGA PG-9087, also known as the Red Knight / Red Samurai, is a fairly cheap bluetooth controller (can be found on eBay for around £15). It's one of those retractable control pads that can clamp around a handheld device (in my case an Android phone) to make a Nintendo Switch style handheld gaming console. It also works quite well as a standalone controller, but I couldn't get mine to work with RetroPie out of the box. After lots of trial and error and trying out things on this forum I've got it working perfectly. Thought I'd share how I got it to work here in case someone has similar issues with this controller or a similar model. Feel free to reply if anything isn't clear or if you need more information!

• Review Ipega 9087 Pro
• Review Ipega 9087 Case
• Ipega 9087 Review
• Review Ipega 9087 Review
• Review Ipega 9087 Ultra

Step 1: Pairing the controller with RetroPie
This part is pretty straightforward. Put the device into pairing mode and pair it from the Bluetooth option of the RetroPie menu in emulationstation. After this the device works in the bluetooth menu, but frustratingly, not in emulationstation!

Play like a Pro on your Android Phone or Tablet, or even your Windows PC. The iPega 9087 has a telescopic holder to fit Android devices up to 6.2 inches. It comes with dual analogue joysticks, a D-Pad and twelve gaming buttons. In this video, let's take a closer look at the IPEGA Red Knight. Also known as PG-9087s. Let's see how can this controller makes you feel like you're playing on a handheld console. If you're interested in getting this device, I shared the link to where I purchased mine. Ipega Red Knight PG-9087s. Apr 19, 2016 IPEGA Game Center The IPEGA Game Center APK is a file that you would normally install on your tablet or smartphone when you intend to pair your wireless IPEGA gamepad with your device. The issue with using the IPEGA Game Center APK however is the fact that the configuration process can be quite cumbersome, often resulting in great frustration. IPega Pg-9087S Product Show 1.This Gamepad support playing games on Bluetooth enabled Android/iOS devices and Win 7/8/10 systerms PC without any drivers. 2.Applicable devices: Smartphone/tablet/smart TV, set-top box/ Windows PC 3.Support TURBO(acceleration) function, make it stronger and more fast when playing games. 4.Designed with telescopic.

Step 2: Getting the controller to work with emulation station
Here you're adding a rule to tell the pi how it should communicate with the controller (I think!!):
1.) At the main screen, press F4 to drop to the command line (or SSH in using putty)
2.) Type 'sudo nano /etc/udev/rules.d/55-local.rules' to create a new udev rule file containing the following entry:
SUBSYSTEM'input', ATTRS{name}'PG-9087', MODE='0666', ENV{ID_INPUT_JOYSTICK}='1'
... if you have a controller with a different name, substitute PG-9087 for the name of your controller as it appeared when pairing your device in the step above
3.) Press CTRL+X and save the changes
4.) Exit the command line by typing 'reboot' or 'exit'
... now the controller will work in emulationstation but not RetroArch!
My version can be found here: https://github.com/HumanRob/PG-9087-with-RetroPie/blob/master/55-local.rules

Review Ipega 9087 Pro

Credit for this goes to the following posts, which accomplished similar things with different controllers:
https://www.amazon.com/gp/customer-reviews/R3GVRHP307ROSX/ref=cm_cr_arp_d_rvw_ttl?ie=UTF8&ASIN=B01N8WWOE5

Step 3: Getting the controller to work in RetroArch.
Launch retroarch and you should hopefully see that the direction pad works but none of the buttons do. To fix this we need to edit the file:
/opt/retropie/configs/all/retroarch-joypads/PG-9087.cfg (which should be automatically created, if not try launch a game via retroarch and check again)
... and tell retroarch what to map each button to. There are 2 ways to do this:

Option 1: Follow meleu's excellent post here:
https://retropie.org.uk/forum/topic/2719/keyboard-stopped-working-after-i-played-around-in-the-controller-config-in-rtgui/3
... to map the controls yourself in retropie and then copy the values to PG-9087.cfg. This option is best if you're trying this on a different controller or option 2 didn't give the results you wanted

Review Ipega 9087 Case

Option 2: copy my PG-9087.cfg into the /configs/all/retroarch-joypads/ directory. The file itself can be found here: https://github.com/HumanRob/PG-9087-with-RetroPie/blob/master/PG-9087.cfg
...Or copy the values into your own file:
input_device = 'PG-9087'
input_driver = 'udev'
input_r_y_plus_axis = '+3'
input_r_x_minus_axis = '-2'
input_l_btn = '16'
input_load_state_btn = '16'
input_start_btn = '21'
input_exit_emulator_btn = '21'
input_r_y_minus_axis = '-3'
input_down_btn = 'h0down'
input_l_x_plus_axis = '+0'
input_r_btn = '17'
input_save_state_btn = '17'
input_right_btn = 'h0right'
input_state_slot_increase_btn = 'h0right'
input_select_btn = '20'
input_left_btn = 'h0left'
input_state_slot_decrease_btn = 'h0left'
input_l2_btn = '18'
input_l_y_minus_axis = '-1'
input_up_btn = 'h0up'
input_a_btn = '11'
input_b_btn = '10'
input_reset_btn = '10'
input_enable_hotkey_btn = '24'
input_l_y_plus_axis = '+1'
input_r2_btn = '11'
input_x_btn = '14'
input_menu_toggle_btn = '14'
input_l_x_minus_axis = '-0'
input_y_btn = '13'
input_r_x_plus_axis = '+2'
input_l3_btn = '23'

Ipega 9087 Review

... after this restart, connect the controller and it should work perfectly!

Review Ipega 9087 Review

Review Ipega 9087 Ultra

Bonus Step 4: script to automatically re-pair and connect to the controller.
I also use this controller with my android phone, and I found that after I'd used it with my phone it wouldn't connect to my raspberry pi. I found the only way to fix this was to remove the device via the RetroPie bluetooth menu and pair it again, which was a big hassle. To avoid this I created an .sh script file which does all this for me. If I find that the controller isn't connecting I run this script and it connects straight away (I execute the script via SSH on my phone but you could include it at startup or anywhere you like). The script can be found here: https://github.com/HumanRob/PG-9087-with-RetroPie/blob/master/bluetoothpair.sh
... you must replace the mac address with the mac address of your own device, which you can find in RetroPie's bluetooth menu.