| Harald Welte | 1d12caa | 2022-11-01 09:32:22 +0100 | [diff] [blame^] | 1 | [[hardware]] |
| 2 | == e1-tracer Hardware |
| 3 | |
| 4 | The e1-tracer Hardware consists of a single circuit board, mechanically |
| 5 | either assembled into a desktop enclosure (KOH variant) or into a 3U component |
| 6 | carrier module (BGT variant). |
| 7 | |
| 8 | image::images/e1_tracer-bgt-front.jpg[width=400,title="e1-tracer BGT variant"] |
| 9 | image::images/e1_tracer-koh1.jpg[width=400,title="e1-tracer KOH variant"] |
| 10 | |
| 11 | |
| 12 | It's main building blocks are: |
| 13 | |
| 14 | * an iCE40 FPGA |
| 15 | * two E1 Line Interface Unit ICs |
| 16 | * two E1 line interface analog (transformers, biasing networks and ESD protection) |
| 17 | |
| 18 | === Schematics / Board Layout |
| 19 | |
| 20 | As e1-tracer is an OSHW (Open Source Hardware) project, the full schematics |
| 21 | and design files are publicly available. |
| 22 | |
| 23 | The design files in EAGLE format are available at https://git.osmocom.org/osmo-e1-hardware/tree/hardware/e1-tracer |
| 24 | |
| 25 | PDF rendered schematics are available at https://gitea.osmocom.org/retronetworking/osmo-e1-hardware/raw/branch/master/hardware/e1-tracer/e1-tracer_sch.pdf |
| 26 | |
| 27 | === Connectors / LEDs |
| 28 | |
| 29 | image::images/e1-tracer-plate.png[width=400,title="front side of e1-tracer"] |
| 30 | |
| 31 | From left to right, there are the following LED indcators, connectors and buttons: |
| 32 | |
| 33 | * LED block with 4 LED's |
| 34 | * Primary E1 Port (E1 A) |
| 35 | * Secondary E1 Port (E1 B) |
| 36 | * Serial Console Connector |
| 37 | * USB Connector |
| 38 | * Bootloader Button |
| 39 | |
| 40 | ==== LEDs |
| 41 | |
| 42 | The left-most column of LEDs consists of two red *LOS LEDs*. |
| 43 | They indicate a LOS (Loss Of Signal) condition for the respective E1 direction. It is normal for the LEDs to be illuminated even in presence of a valid E1 signal until the host software has fully initialized the firmware for the first time after power-up. |
| 44 | |
| 45 | The right column of LEDs consists of two further LEDs: |
| 46 | |
| 47 | * a multi-color *STATUS LED* on the top |
| 48 | * a green *POWER LED* on the bottom |
| 49 | |
| 50 | The *STATUS LED* is used by the firmware to indicate a variety of status |
| 51 | information. Pleas see the firmware documentation in <<firmware>>. |
| 52 | |
| 53 | The green *POWER LED* is illuminated as soon as the device has DC power. |
| 54 | |
| 55 | ==== J1A and J1B: E1 Interface Connectors |
| 56 | |
| 57 | There are two RJ45 connectors next to each other. |
| 58 | |
| 59 | Those are the connections for your symmetric 120 Ohms E1 interface |
| 60 | circuit. You insert the e1-tracer into your E1 link. The two ports are |
| 61 | internally wired straight-through, so you can insert the e1-tracer into |
| 62 | your E1 link. |
| 63 | |
| 64 | The actual tracing functionality is implemented via a high-impedance |
| 65 | tap, which will not disturb the normal E1 communications link. The link |
| 66 | remains unaffected even if the e1-tracer is unpowered. |
| 67 | |
| 68 | .Pin-out of RJ45 E1 connectors |
| 69 | [options="header"] |
| 70 | |=== |
| 71 | | Pin | Function (TE) | Function (NT Mode) |
| 72 | | 1 | Pair A | Pair A |
| 73 | | 2 | Pair A | Pair A |
| 74 | | 3 | not used | not used |
| 75 | | 4 | Pair B | Pair B |
| 76 | | 5 | Pair B | Pair B |
| 77 | | 7 | not used | not used |
| 78 | | 8 | not used | not used |
| 79 | |=== |
| 80 | |
| 81 | NOTE: E1 cables use RJ45 like Ethernet, but Ethernet cables have a |
| 82 | different pin-out. Particularly, you cannot use an Ethernet cross-over |
| 83 | cable as an E1 cross-over! |
| 84 | |
| 85 | ==== X1: USB Connector |
| 86 | |
| 87 | The USB connector is a USB Mini B connector. The e1-tracer uses |
| 88 | USB 1.1 full-speed signals. As the e1-tracer is a bus-powered device, |
| 89 | 5V DC power is also sourced from this connector. |
| 90 | |
| 91 | ==== X2: Serial Console Connector |
| 92 | |
| 93 | The serial console is used for development and debugging. It uses an |
| 94 | Osmocom-style 2.5mm stereo TRS jack. |
| 95 | |
| 96 | The serial console uses 3.3V CMOS logic levels |
| 97 | |
| 98 | The serial console uses a rate of 1000000 bps. |
| 99 | |
| 100 | The pin-out is as follows: |
| 101 | |
| 102 | * Tip: Tx output from PC (Rx input of e1-tracer) |
| 103 | * Ring: Rx input of PC (Tx output of e1-tracer) |
| 104 | * Shield: GND |
| 105 | |
| 106 | A compatible cable can be sourced from the sysmocom web-shop at |
| 107 | http://shop.sysmocom.de/. |
| 108 | |
| 109 | Note that CP2102 based cables require special programming to support |
| 110 | the baud rate of 1000000 (as opposed to the more standard 921600). |
| 111 | |
| 112 | [[hw-pushbutton]] |
| 113 | === Bootloader Button |
| 114 | |
| 115 | There is a push-button next to the _USB B connector_. It is recessed |
| 116 | to protect against accidental use. You will need to use a paper clip, |
| 117 | pen tip or other similar object to push it. |
| 118 | |
| 119 | The button, when pressed while power-up, can be used to force booting |
| 120 | into the DFU loader in order to recover from a broken firmware |
| 121 | installation. |
| 122 | |
| 123 | |