[[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 <>. 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.