157 lines
4.8 KiB
Plaintext
157 lines
4.8 KiB
Plaintext
[[hardware]]
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== icE1usb Hardware
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The icE1usb Hardware consists of a single circuit board (in an optional
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enclosure).
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It's main building blocks are:
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* an iCE40 FPGA
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* Two E1 line interface (transformers, biasing networks and ESD protection) footnote:[Second interface requires firmware >= 0.2 and OHCI/OHCI/EHCI host controller]
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* a GPS receiver module with 1PPS output to the FPGA footnote:[Requires firmware >= 0.2]
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=== Schematics
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As icE1usb is an OSHW (Open Source Hardware) project, the full schematics
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and design files are publicly available.
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The design files in KiCAD format are available at https://git.osmocom.org/osmo-e1-hardware/tree/hardware/icE1usb
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PDF rendered schematics are available at https://git.osmocom.org/osmo-e1-hardware/plain/hardware/icE1usb/r1.0/icE1usb.pdf
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=== Connectors on E1 side
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image::images/icE1usb-e1_side.jpg[width=400,title="E1 side of icE1usb"]
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From left to right, there are the following connectors:
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* X5A: Primary E1 Port
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* X5B: Secondary E1 Port
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==== X5A and X5B: E1 Interface Connectors
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On one side of the PCB there are two RJ45 connectors next to each other.
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Those are the two E1 line interfaces. The interfaces are of symmetric
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120 Ohms type.
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Assuming the board is oriented with the tab of the RJ45 connectors facing
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up:
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* Interface 0 is on the right side
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* Interface 1 is on the left side (next to the button)
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The pin-out of the connectors can be swapped between TE and NT mode using
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the J4 and J5 jumper blocks on the circuit board.
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The factory default setting of the jumpers is TE-mode.
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In case you're using the icE1usb with user-side equipment such as a GSM BTS,
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a PBX, a Router or the like which traditionally was attached to the public
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network, those devices all implement TE mode. In such situations you need
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to either switch the icE1usb to NT mode (and use straight wiring), or use
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an E1 cross-over cable.
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.Pin-out of RJ45 E1 connectors
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[options="header"]
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|===
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| Pin | Function (TE) | Function (NT Mode)
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| 1 | Rx | Tx
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| 2 | Rx | Tx
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| 3 | not used | not used
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| 4 | Tx | Rx
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| 5 | Tx | Rx
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| 7 | not used | not used
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| 8 | not used | not used
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|===
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NOTE: E1 cables use RJ45 like Ethernet, but Ethernet cables have a
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different pin-out. Particularly, you cannot use an Ethernet cross-over
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cable as an E1 cross-over!
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==== Switching between TE/NT mode
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To change the mode, unscrew the 2 PH0 screws on the side with the 2 RJ45 jacks. You'll also need to unscrew the nut on the SMA jack on the other side.
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After that, the cover plate and rubber gasket around the 2 RJ45 jacks can be removed. The PCB can be slid out of the case.
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[frame="none"]
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[grid="none"]
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|===
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|image:images/te_t.png[width=250,title="icE1usb jumpered for TE mode"] |image:images/nt_t.png[width=250,title="icE1usb jumpered for NT mode"]
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| *TE mode* (default) | *NT mode* |
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|===
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Each 2x4 jumper block is connected to the nearest RJ45 connector.
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=== Connectors on USB side
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image::images/icE1usb-usb_side.jpg[width=400,title="USB side of icE1usb"]
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From left to right, there are the following connectors:
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* X1: GPS Antenna Connector
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* X2: Serial Console Connector
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* X4: USB Connector
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* X3: GPIO / Extension Connector
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==== X4: USB Connector
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The USB connector is a USB Type C connector. However, it only carries
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USB 1.1 full-speed signals. 5V DC power is also sourced from this
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connector.
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==== X2: Serial Console Connector
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The serial console is used for development and debugging. It uses an
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Osmocom-style 2.5mm stereo TRS jack.
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The serial console uses 3.3V CMOS logic levels
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The serial console uses a rate of 1000000 bps.
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The pin-out is as follows:
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* Tip: Tx output from PC (Rx input of icE1usb)
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* Ring: Rx input of PC (Tx output of icE1usb)
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* Shield: GND
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A compatible cable can be sourced from the sysmocom web-shop at
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http://shop.sysmocom.de/.
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==== X1: GPS Antenna Connector
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The GPS antenna connector is a female SMA connector.
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You can connect most standard active GPS antennas with built-in LNA.
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icE1us provide phantom voltage.
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The use of a GPS antenna is only required when you need a high precision
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clock reference for the 2.048 MHz E1 bit clock, e.g. to provide a clock
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reference to a cellular base station on the A-bis interface.
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==== X3: GPIO / Extension Connector
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This is a RJ45 connector adjacent to the USB connector.
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It is currently unused and reserved for future use.
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[[hw-pushbutton]]
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=== Pushbutton
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This is a push-button next to the _E1 interface '1'_. It is recessed
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to protect against accidental use. You will need to use a paper clip,
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pen tip or other similar object to push it.
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The button can be used to force booting into the DFU loader in order to
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recover from a broken firmware installation.
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=== Multi-Color LED
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Above the USB-C connector, there is a multi-color RGB LED.
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This LED is used by the firmware to indicate a variety of status
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information. Pleas see the firmware documentation in <<firmware>>.
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