| [[hardware]] |
| == e1-tracer Hardware |
| |
| The e1-tracer Hardware consists of a single circuit board, mechanically |
| either assembled into a desktop enclosure (KOH variant) or into a 3U component |
| carrier module (BGT variant). |
| |
| image::images/e1_tracer-bgt-front.jpg[width=400,title="e1-tracer BGT variant"] |
| image::images/e1_tracer-koh1.jpg[width=400,title="e1-tracer KOH variant"] |
| |
| |
| It's main building blocks are: |
| |
| * an iCE40 FPGA |
| * two E1 Line Interface Unit ICs |
| * two E1 line interface analog (transformers, biasing networks and ESD protection) |
| |
| === Schematics / Board Layout |
| |
| As e1-tracer is an OSHW (Open Source Hardware) project, the full schematics |
| and design files are publicly available. |
| |
| The design files in EAGLE format are available at https://git.osmocom.org/osmo-e1-hardware/tree/hardware/e1-tracer |
| |
| PDF rendered schematics are available at https://gitea.osmocom.org/retronetworking/osmo-e1-hardware/raw/branch/master/hardware/e1-tracer/e1-tracer_sch.pdf |
| |
| === Connectors / LEDs |
| |
| image::images/e1-tracer-plate.png[width=400,title="front side of e1-tracer"] |
| |
| From left to right, there are the following LED indcators, connectors and buttons: |
| |
| * LED block with 4 LED's |
| * Primary E1 Port (E1 A) |
| * Secondary E1 Port (E1 B) |
| * Serial Console Connector |
| * USB Connector |
| * Bootloader Button |
| |
| ==== LEDs |
| |
| The left-most column of LEDs consists of two red *LOS LEDs*. |
| 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. |
| |
| The right column of LEDs consists of two further LEDs: |
| |
| * a multi-color *STATUS LED* on the top |
| * a green *POWER LED* on the bottom |
| |
| The *STATUS LED* is used by the firmware to indicate a variety of status |
| information. Pleas see the firmware documentation in <<firmware>>. |
| |
| The green *POWER LED* is illuminated as soon as the device has DC power. |
| |
| ==== J1A and J1B: E1 Interface Connectors |
| |
| There are two RJ45 connectors next to each other. |
| |
| Those are the connections for your symmetric 120 Ohms E1 interface |
| circuit. You insert the e1-tracer into your E1 link. The two ports are |
| internally wired straight-through, so you can insert the e1-tracer into |
| your E1 link. |
| |
| The actual tracing functionality is implemented via a high-impedance |
| tap, which will not disturb the normal E1 communications link. The link |
| remains unaffected even if the e1-tracer is unpowered. |
| |
| .Pin-out of RJ45 E1 connectors |
| [options="header"] |
| |=== |
| | Pin | Function (TE) | Function (NT Mode) |
| | 1 | Pair A | Pair A |
| | 2 | Pair A | Pair A |
| | 3 | not used | not used |
| | 4 | Pair B | Pair B |
| | 5 | Pair B | Pair B |
| | 7 | not used | not used |
| | 8 | not used | not used |
| |=== |
| |
| NOTE: E1 cables use RJ45 like Ethernet, but Ethernet cables have a |
| different pin-out. Particularly, you cannot use an Ethernet cross-over |
| cable as an E1 cross-over! |
| |
| ==== X1: USB Connector |
| |
| The USB connector is a USB Mini B connector. The e1-tracer uses |
| USB 1.1 full-speed signals. As the e1-tracer is a bus-powered device, |
| 5V DC power is also sourced from this connector. |
| |
| ==== X2: Serial Console Connector |
| |
| The serial console is used for development and debugging. It uses an |
| Osmocom-style 2.5mm stereo TRS jack. |
| |
| The serial console uses 3.3V CMOS logic levels |
| |
| The serial console uses a rate of 1000000 bps. |
| |
| The pin-out is as follows: |
| |
| * Tip: Tx output from PC (Rx input of e1-tracer) |
| * Ring: Rx input of PC (Tx output of e1-tracer) |
| * Shield: GND |
| |
| A compatible cable can be sourced from the sysmocom web-shop at |
| http://shop.sysmocom.de/. |
| |
| Note that CP2102 based cables require special programming to support |
| the baud rate of 1000000 (as opposed to the more standard 921600). |
| |
| [[hw-pushbutton]] |
| === Bootloader Button |
| |
| There is a push-button next to the _USB B connector_. It is recessed |
| to protect against accidental use. You will need to use a paper clip, |
| pen tip or other similar object to push it. |
| |
| The button, when pressed while power-up, can be used to force booting |
| into the DFU loader in order to recover from a broken firmware |
| installation. |
| |
| |