USB host

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(→‎added discussion of charge rates, and how to manually set charge rate)
(extracted custom usb cables to a separate page)
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The mini-USB port on both the Neo 1973 and the Neo FreeRunner supports both USB host and USB device. This opens up a range of possibilities, such as adding USB cameras and USB input devices.
 
The mini-USB port on both the Neo 1973 and the Neo FreeRunner supports both USB host and USB device. This opens up a range of possibilities, such as adding USB cameras and USB input devices.
  
−
By default, the mini-USB port is in device mode. To tell the device that it is logically a host:
+
=== Selecting USB host mode ===
 +
 
 +
By default, the mini-USB port is in device mode. To tell the Neo that it is logically a host:
  
 
  echo "host" > /sys/devices/platform/s3c2410-ohci/usb_mode
 
  echo "host" > /sys/devices/platform/s3c2410-ohci/usb_mode
  
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Instruct the device to provide 5 volts (not available on Neo 1973):
+
Independent of the logical mode of the USB port, the Neo FreeRunner can provide 5 volt USB power to an attached USB device. To enable this (not available on Neo 1973):
  
 
  echo "1" > /sys/devices/platform/neo1973-pm-host.0/hostmode
 
  echo "1" > /sys/devices/platform/neo1973-pm-host.0/hostmode
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Available power in host mode is limited to 500mA on the Neo FreeRunner, and no power is available in host mode on the Neo 1973. If your USB devices consumes less than 500mA, you may connect it directly to your Neo FreeRunner.
 
Available power in host mode is limited to 500mA on the Neo FreeRunner, and no power is available in host mode on the Neo 1973. If your USB devices consumes less than 500mA, you may connect it directly to your Neo FreeRunner.
  
−
To power USB-host-mode on Neo 1973, or if you want to apply external power to Neo FreeRunner while in host-mode, you can provide power by using a powered USB hub (see below), or by manually injecting power into the attached USB device (and Neo FreeRunner) via a modified USB cable (Y-cable (C)jr, described further below).
+
To provide power to USB devices attached to your Neo 1973, or to provide more power than your Neo FreeRunner can provide, you can provide power by using a powered USB hub (see below), or by manually injecting power into the attached USB device (and Neo FreeRunner) via one of the [[specialized_USB_cables]].
  
 
=== Powered USB hubs known to work with the Neo ===
 
=== Powered USB hubs known to work with the Neo ===
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  echo "1" > /sys/devices/platform/neo1973-pm-host.0/hostmode
 
  echo "1" > /sys/devices/platform/neo1973-pm-host.0/hostmode
  
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Next, power must somehow be injected. An unmodified powered USB hub only provides power to the connected devices, but not to the connected host, so the only solution here is to modify a USB-hub¹) or to create a custom cable which will inject power into the host.
+
Next, power must somehow be injected. An unmodified powered USB hub only provides power to the connected devices, but not to the connected host, so the only solution here is to modify a USB-hub¹) or to create a custom cable which will inject power into the host. See [[specialized_USB_cables]] for some examples.
  
 
Finally, there is the question of charge rate. The charging logic in the Neo will only charge at 100mA by default. Charging at 500mA will take place only if the charging device responds appropriatly to USB negotiation to increase power consumption. Charging at 1000mA will only take place if the Neo detects the appropriate resistor on the ID pins.
 
Finally, there is the question of charge rate. The charging logic in the Neo will only charge at 100mA by default. Charging at 500mA will take place only if the charging device responds appropriatly to USB negotiation to increase power consumption. Charging at 1000mA will only take place if the Neo detects the appropriate resistor on the ID pins.
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¹) often it's sufficient to short a diode in USB-hub to feed power to the host-connector too.
 
¹) often it's sufficient to short a diode in USB-hub to feed power to the host-connector too.
  
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=== Modified USB cable to inject power while in host mode ===
 
  
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Three-headed cables are required if you want to power the FreeRunner / USB device whilst in host mode.  For many uses the FreeRunner provides sufficient power to make such a cable unnecessary. At the moment, you'll have to manufacture this one yourself. You need to make a cable with three ends:
 
−
 
−
* A mini-USB type B cable for the Neo itself
 
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* A cable of whatever type to go to your USB device.
 
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* A cable going to a +5V +/-10%(max!) power supply with enough power for your device and to charge the Neo. This could be a wall charger or even another USB plug.
 
−
 
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You connect the Data+ and Data- wires of the Neo and the device, and connect all of the ground wires together and all of the +5V wires together. This powers the Neo and the device, while letting the neo talk to the device.
 
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You have to connect 2pcs  15kOhm resistors, one from D+ to ground, and one from D- to ground, to comply with USB-spec for hostmode, as Neo is switching off the internal resistors when you enable charging/powering over USB by asserting EN_USBHOST.
 
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See schematics, LOCATION:49XX
 
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Just for reference, the USB wires from left to right are:
 
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*Black: Power -
 
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*Green: Data -
 
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*White: Data +
 
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*Red: Power +
 
−
 
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The Mini_USB-B connector has a fifth pin, the ID-pin.
 
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This pin is supposed to be short to ground to signal Freerunner to enter hostmode. For the Y-cable and enabling external power while in hostmode, you may connect a 47kOhm resistor from ID-pin to ground. This is the same trick the OM-wallcharger uses to signal to Freerunner it can charge with 1A. Future kernels should switch to hostmode + external power when seeing this 47k resistor.
 
  
 
=== Power Concerns ===
 
=== Power Concerns ===
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(Also this should be done by kernel when seeing 47K at ID-pin)
 
(Also this should be done by kernel when seeing 47K at ID-pin)
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== DIY USB host adapter ==
 
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Note that these instructions are provided in the hope that they are useful but without any warranty!
 
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[[Image:2-usb-receptables.jpg]]
 
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:#Find an old motherboard with a set of two USB receptacles as shown above.
 
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:#Desolder this set of receptacles from the motherboard. This can be bit tricky but it is doable at least with a desoldering gun.
 
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:#Each receptacle has four pins. Use a multimeter to verify that you have no short circuits between the pins or the shield.
 
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:#Solder adjacent pins together (GND to GND, D- to D-, D+ to D+, VCC to VCC).
 
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:#(Optional) Build a test cable. Cut an USB cable with A plug into half, connect it a receptacle and again measure that you have no short circuits. Then connect the test cable to PC and verify that you see
 
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black GND
 
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green 0V
 
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white 0V
 
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red +5V
 
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:#Freerunner is shipped with a mini-B-to-A-plug cable. Connect this to a receptacle.
 
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:#(Optional)Connect test cable to the other receptacle and verify that you see
 
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black GND
 
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green 0V
 
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white 0V
 
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red 0V
 
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when freerunner acts as a device and
 
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black GND
 
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green 0V
 
−
white 0V
 
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red +5V
 
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when it acts as a host.
 
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:#At your own risk, switch freerunner to USB host mode and connect an USB device to the other receptacle of the adapter. Here's how the setup should look like:
 
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[[Image:Usb-gender-changer1.jpg]]
 
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[[Image:Usb-gender-changer2.jpg]]
 
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=== Compatibility ===
 
−
 
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The adapter works with kingston data traveller 4G memory stick and aiptec pencam webcam. However, for some reason (probably the missing 15k resistors at D+ and D-) it did not work with any of the tested USB keyboards or mice:
 
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usb 1-2: new full speed USB device using s3c2410-ohci and address 24
 
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usb 1-2: device descriptor read/64, error -62
 
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usb 1-2: device descriptor read/64, error -62
 
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usb 1-2: new full speed USB device using s3c2410-ohci and address 25
 
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usb 1-2: device descriptor read/64, error -62
 
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usb 1-2: device descriptor read/64, error -62
 
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usb 1-2: new full speed USB device using s3c2410-ohci and address 26
 
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usb 1-2: device not accepting address 26, error -62
 
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usb 1-2: new full speed USB device using s3c2410-ohci and address 27
 
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usb 1-2: device not accepting address 27, error -62
 
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However, if I connect neo to small (unpowered) USB hub
 
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usb 1-2: new full speed USB device using s3c2410-ohci and address 61
 
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usb 1-2: configuration #1 chosen from 1 choice
 
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hub 1-2:1.0: USB hub found
 
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hub 1-2:1.0: 4 ports detected
 
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and connect the keyboard to the hub then it is correctly recognized:
 
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usb 1-2.3: new low speed USB device using s3c2410-ohci and address 62
 
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usb 1-2.3: configuration #1 chosen from 1 choice
 
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input:  USB Keyboard as /devices/platform/s3c2410-ohci/usb1/1-2/1-2.3/1-2.3:1.0/input/input13
 
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input: USB HID v1.10 Keyboard [  USB Keyboard] on usb-s3c24xx-2.3
 
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input:  USB Keyboard as /devices/platform/s3c2410-ohci/usb1/1-2/1-2.3/1-2.3:1.1/input/input14
 
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input: USB HID v1.10 Device [  USB Keyboard] on usb-s3c24xx-2.3
 
−
 
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With the hub I can also use both keyboard and usb memory stick at the same time.
 
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=== Power consumption ===
 
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When I unplug the USB hub (with only keyboard connected to it) the power consumption estimate at /sys/devices/platform/bq2700-battery.0/power_supply/bat/current_now decreases from 175000 to 145000 (are these microamperes?).
 
  
 
[[Category:Neo1973 Hardware]]
 
[[Category:Neo1973 Hardware]]
 +
[[Category:Neo FreeRunner Hardware]]
 
[[Category:USB]]
 
[[Category:USB]]

Revision as of 09:23, 29 August 2008

Contents

USB host

The mini-USB port on both the Neo 1973 and the Neo FreeRunner supports both USB host and USB device. This opens up a range of possibilities, such as adding USB cameras and USB input devices.

Selecting USB host mode

By default, the mini-USB port is in device mode. To tell the Neo that it is logically a host: 

echo "host" > /sys/devices/platform/s3c2410-ohci/usb_mode

Independent of the logical mode of the USB port, the Neo FreeRunner can provide 5 volt USB power to an attached USB device. To enable this (not available on Neo 1973): 

echo "1" > /sys/devices/platform/neo1973-pm-host.0/hostmode

Note: You may want to run ifconfig usb0 down prior to switching to USB host mode, as the Neo's USB networking may not like having its USB port disappear. You'll probably want to ssh into your Neo over WiFi or Bluetooth before starting all of this, alternatively use an on screen keyboard.

Providing power to connected USB devices while in host mode

Normally, USB host ports provide power to any connected USB device. In the case of portable handheld devices, this power may be limited. (Usually the battery is sized to power the handheld device alone, and to maximize standby time.)

Available power in host mode is limited to 500mA on the Neo FreeRunner, and no power is available in host mode on the Neo 1973. If your USB devices consumes less than 500mA, you may connect it directly to your Neo FreeRunner.

To provide power to USB devices attached to your Neo 1973, or to provide more power than your Neo FreeRunner can provide, you can provide power by using a powered USB hub (see below), or by manually injecting power into the attached USB device (and Neo FreeRunner) via one of the specialized_USB_cables.

Powered USB hubs known to work with the Neo

(please add any known to work)

Providing power to run and charge the Neo while in host mode

A slightly separate issue is power to run and charge the Neo (both types) itself. When the USB port is in device mode, the Neo FreeRunner/1973 can be powered and recharged via the USB port, but when in standard host mode, the Neo FreeRunner is set to provide power and does not charge. Fortunately, control of the direction of power (in or out) is independent of the personality of the USB port (host or device):

To recap, the direction of power can be controlled:

Set to 0 (default), no power is provided at the USB port, charging is enabled, and host 15K pulldowns are removed from D+ and D-: 

echo "0" > /sys/devices/platform/neo1973-pm-host.0/hostmode

Set to 1, provides up to 500mA USB power at the USB port (FreeRunner only), disables charging from USB, and applies 15K pulldowns to USB D+ and D-: 

echo "1" > /sys/devices/platform/neo1973-pm-host.0/hostmode

Next, power must somehow be injected. An unmodified powered USB hub only provides power to the connected devices, but not to the connected host, so the only solution here is to modify a USB-hub¹) or to create a custom cable which will inject power into the host. See specialized_USB_cables for some examples.

Finally, there is the question of charge rate. The charging logic in the Neo will only charge at 100mA by default. Charging at 500mA will take place only if the charging device responds appropriatly to USB negotiation to increase power consumption. Charging at 1000mA will only take place if the Neo detects the appropriate resistor on the ID pins.

You can manually set the charge rate. See Forcing_fast_charge_mode

¹) often it's sufficient to short a diode in USB-hub to feed power to the host-connector too.


Power Concerns

You'll need to force the Neo to go into fast charge mode, since it can't do its usual power negotiation over USB. 

echo -n "fast_cccv" >  /sys/devices/platform/s3c2410-i2c/i2c-adapter/i2c-0/0-0008/chgmode

(Also this should be done by kernel when seeing 47K at ID-pin)

Retrieved from "http://openmoko.org/index.php?title=USB_host&oldid=50433"
Personal tools

USB host

The mini-USB port on both the Neo 1973 and the Neo FreeRunner supports both USB host and USB device. This opens up a range of possibilities, such as adding USB cameras and USB input devices.

Selecting USB host mode

By default, the mini-USB port is in device mode. To tell the Neo that it is logically a host: 

echo "host" > /sys/devices/platform/s3c2410-ohci/usb_mode

Independent of the logical mode of the USB port, the Neo FreeRunner can provide 5 volt USB power to an attached USB device. To enable this (not available on Neo 1973): 

echo "1" > /sys/devices/platform/neo1973-pm-host.0/hostmode

Note: You may want to run ifconfig usb0 down prior to switching to USB host mode, as the Neo's USB networking may not like having its USB port disappear. You'll probably want to ssh into your Neo over WiFi or Bluetooth before starting all of this, alternatively use an on screen keyboard.

Providing power to connected USB devices while in host mode

Normally, USB host ports provide power to any connected USB device. In the case of portable handheld devices, this power may be limited. (Usually the battery is sized to power the handheld device alone, and to maximize standby time.)

Available power in host mode is limited to 500mA on the Neo FreeRunner, and no power is available in host mode on the Neo 1973. If your USB devices consumes less than 500mA, you may connect it directly to your Neo FreeRunner.

To provide power to USB devices attached to your Neo 1973, or to provide more power than your Neo FreeRunner can provide, you can provide power by using a powered USB hub (see below), or by manually injecting power into the attached USB device (and Neo FreeRunner) via one of the specialized_USB_cables.

Powered USB hubs known to work with the Neo

(please add any known to work)

Providing power to run and charge the Neo while in host mode

A slightly separate issue is power to run and charge the Neo (both types) itself. When the USB port is in device mode, the Neo FreeRunner/1973 can be powered and recharged via the USB port, but when in standard host mode, the Neo FreeRunner is set to provide power and does not charge. Fortunately, control of the direction of power (in or out) is independent of the personality of the USB port (host or device):

To recap, the direction of power can be controlled:

Set to 0 (default), no power is provided at the USB port, charging is enabled, and host 15K pulldowns are removed from D+ and D-: 

echo "0" > /sys/devices/platform/neo1973-pm-host.0/hostmode

Set to 1, provides up to 500mA USB power at the USB port (FreeRunner only), disables charging from USB, and applies 15K pulldowns to USB D+ and D-: 

echo "1" > /sys/devices/platform/neo1973-pm-host.0/hostmode

Next, power must somehow be injected. An unmodified powered USB hub only provides power to the connected devices, but not to the connected host, so the only solution here is to modify a USB-hub¹) or to create a custom cable which will inject power into the host. See specialized_USB_cables for some examples.

Finally, there is the question of charge rate. The charging logic in the Neo will only charge at 100mA by default. Charging at 500mA will take place only if the charging device responds appropriatly to USB negotiation to increase power consumption. Charging at 1000mA will only take place if the Neo detects the appropriate resistor on the ID pins.

You can manually set the charge rate. See Forcing_fast_charge_mode

¹) often it's sufficient to short a diode in USB-hub to feed power to the host-connector too.


Power Concerns

You'll need to force the Neo to go into fast charge mode, since it can't do its usual power negotiation over USB. 

echo -n "fast_cccv" >  /sys/devices/platform/s3c2410-i2c/i2c-adapter/i2c-0/0-0008/chgmode

(Also this should be done by kernel when seeing 47K at ID-pin)