Harald Welte | d645d44 | 2020-12-14 19:20:38 +0100 | [diff] [blame] | 1 | [[hardware]] |
| 2 | == icE1usb Hardware |
| 3 | |
| 4 | The icE1usb Hardware consists of a single circuit board (in an optional |
| 5 | enclosure). |
| 6 | |
| 7 | It's main building blocks are: |
| 8 | |
| 9 | * an iCE40 FPGA |
| 10 | * Two E1 line interface (transformers, biasing networks and ESD protection) footnote:[Only one E1 line supported by firmware so far] |
| 11 | * a GPS receiver module with 1PPS output to the FPGA footnote:[GPS-DO supported by firmware yet] |
| 12 | |
| 13 | === Schematics |
| 14 | |
| 15 | As icE1usb is an OSHW (Open Source Hardware) project, the full schematics |
| 16 | and design files are publicly available. |
| 17 | |
| 18 | The design files in KiCAD formwa are available at https://git.osmocom.org/osmo-e1-hardware/tree/hardware/icE1usb |
| 19 | |
| 20 | PDF rendered schematics are available at https://git.osmocom.org/osmo-e1-hardware/plain/hardware/icE1usb/r1.0/icE1usb.pdf |
| 21 | |
| 22 | === Connectors |
| 23 | |
| 24 | ==== X5A and X5B: E1 Interface Connectors |
| 25 | |
| 26 | On one side of the PCB there are two RJ45 connectors next to each other. |
| 27 | |
| 28 | Those are the two E1 line interfaces. The interfaces are of symmetric |
| 29 | 120 Ohms type. |
| 30 | |
| 31 | Assuming the board is oriented with the tab of the RJ45 connectors facing |
| 32 | up: |
| 33 | |
| 34 | * Interface 0 is on the right side |
| 35 | * Interface 1 is on the left side (next to the button) |
| 36 | |
| 37 | The pin-out of the connectors can be swapped between TE and NT mode using |
| 38 | the J4 and J5 jumper blocks on the circuit board. |
| 39 | |
| 40 | A GSM BTS typically implements TE pin-out, while the icE1usb should then |
| 41 | use NT mode pin-out if no cross-over cable is used. |
| 42 | |
| 43 | .Pin-out of RJ45 E1 connectors |
| 44 | [options="header"] |
| 45 | |=== |
| 46 | | Pin | Function (TE) | Function (NT Mode) |
| 47 | | 1 | Rx | Tx |
| 48 | | 2 | Rx | Tx |
| 49 | | 3 | not used | not used |
| 50 | | 4 | Tx | Rx |
| 51 | | 5 | Tx | Rx |
| 52 | | 7 | not used | not used |
| 53 | | 8 | not used | not used |
| 54 | |=== |
| 55 | |
| 56 | NOTE: E1 cables use RJ45 like Ethernet, but Ethernet cables have a |
| 57 | different pin-out. Particularly, you cannot use an Ethernet cross-over |
| 58 | cable as an E1 cross-over! |
| 59 | |
| 60 | ==== X4: USB Connector |
| 61 | |
| 62 | The USB connector is a USB Type C connector. However, it only carries |
| 63 | USB 1.1 full-speed signals. 5V DC power is also sourced from this |
| 64 | connector. |
| 65 | |
| 66 | ==== X2: Serial Console Connector |
| 67 | |
| 68 | The serial console is used for development and debugging. It uses an |
| 69 | Osmocom-style 2.5mm stereo TRS jack. |
| 70 | |
| 71 | The serial console uses 3.3V CMOS logic levels |
| 72 | |
| 73 | The serial console uses a rate of 1000000 bps. |
| 74 | |
| 75 | The pin-out is as follows: |
| 76 | |
| 77 | * Tip: Tx output from PC (Rx input of icE1usb) |
| 78 | * Ring: Rx input of PC (Tx output of icE1usb) |
| 79 | * Shield: GND |
| 80 | |
| 81 | A compatible cable can be sourced from the sysmocom web-shop at |
| 82 | http://shop.sysmocom.de/. |
| 83 | |
| 84 | ==== X1: GPS Antenna Connector |
| 85 | |
| 86 | The GPS antenna connector is a female SMA connector. |
| 87 | |
| 88 | You can connect most standard active GPS antennas with built-in LNA. |
| 89 | |
| 90 | icE1us provide phantom voltage. |
| 91 | |
| 92 | The use of a GPS antenna is only required when you need a high precision |
| 93 | clock reference for the 2.048 MHz E1 bit clock, e.g. to provide a clock |
| 94 | reference to a cellular base station on the A-bis interface. |
| 95 | |
| 96 | ==== X3: GPIO / Extension Connector |
| 97 | |
| 98 | This is a RJ45 connector adjacent to the USB connector. |
| 99 | |
| 100 | It is currently unused and reserved for future use. |
| 101 | |
| 102 | |
| 103 | [[hw-pushbutton]] |
| 104 | === Pushbutton |
| 105 | |
| 106 | This is a push-button next to the _E1 interface '1'_. It is recessed |
| 107 | to protect against accidental use. You will need to use a paper clip, |
| 108 | pen tip or other similar object to push it. |
| 109 | |
| 110 | The button can be used to force booting into the DFU loader in order to |
| 111 | recover from a broken firmware installation. |
| 112 | |
| 113 | |
| 114 | === Multi-Color LED |
| 115 | |
| 116 | Above the USB-C connector, there is a multi-color RGB LED. |
| 117 | |
| 118 | This LED is used by the firmware to indicate a variety of status |
| 119 | information. Pleas see the firmware documentation in <<firmware>>. |