Nokia EKSOS N20 DIY carrying case » History » Version 7
laforge, 08/27/2023 11:58 AM
1 | 1 | laforge | h1. Nokia EKSOS N20 DIY carrying case |
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3 | 7 | laforge | {{>toc}} |
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5 | 1 | laforge | In preparation of the first hacker event where we wanted to offer ISDN Uk0 service (see [[ISDN_at_CCC_Camp_2023]]) we wanted to build portable, self-contained and ruggedized systems from the Nokia EKSOS. |
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7 | The systems should contain |
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8 | * EKSOS N20 shelf with mandatory NCU and some subscriber line cards |
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9 | * a number of subscriber ports broken out to RJ45 connectors |
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10 | * a 48V power supply |
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11 | * an [[Osmocom_icE1usb]] plus an embedded Linux board to run TDMoIP for the V5 back-haul |
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12 | ** should have at least two Ethernet ports so we can also back-haul the Q3 management interface to a remote location |
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13 | * some fans for active cooling as it is getting rather hot in the sun outdoor on a camp |
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14 | * ruggedized enclosure to make sure the equipment survives transportation unharmed |
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16 | !20230805_160617.jpg! |
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18 | 1 | laforge | |
19 | h2. Enclosure |
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21 | 3 | laforge | The enclosure is made of wooden panels. |
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23 | h3. wood corpus |
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25 | h4. Assembled enclousre body |
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27 | !20230801_203832.jpg! |
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29 | h4. Milling left and right sides to accomodate screw heads |
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31 | Unfortunately the EKSOS shelf mounting flanges contains a number of screw heads and other protrusions, which require the side panels to be milled |
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33 | !20230801_203546.jpg! |
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35 | h4. Bottom side / gliders |
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37 | !20230801_203821.jpg! |
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39 | 1 | laforge | h3. Fans / Cooling |
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41 | h2. Power Supplies |
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43 | 4 | laforge | The power supplies are mounted in the rear part of the bottom panel |
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45 | !20230804_192817.jpg! |
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47 | h3. 48V: MeanWell RSP-150-48 |
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49 | This supply is used for powering all 3 rails of the EKSOS shelf: |
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50 | * odd numbered line cards |
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51 | * even numbered line cards |
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52 | * signaling voltage |
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54 | I've used the trimmer potentiometer to trim the output voltage to the maximum (+5%). |
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56 | h3. 12V: MeanWell RSP-12-35 |
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58 | This 12V supply is used to power the nanoPi R5S as well as the fans. |
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60 | 5 | laforge | h2. Subscriber port break-out |
61 | 4 | laforge | |
62 | 5 | laforge | Initially, I started with a 1U RJ45 ISDN patch panel at the bottom of the enclosure. Later, I switched to a PCBA + IDC ribbon cable approach to reduce the amount of manual labour. |
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64 | 5 | laforge | h3. Original approach: ISDN patch panel + wiring |
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66 | This approach was implemented in the first two units. It consists of |
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67 | * a 50-port 1U ISDN patch panel mounted to the bottom of the rack |
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68 | * three telephone cables of each 16x2x0.6mm |
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69 | * three DIN connectors |
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70 | * lots of heat shrink tube 1.6mm |
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72 | !20230805_090346.jpg! |
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74 | h3. Updated approach: Ribbon cable, IDC connectors + custom PCBA |
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76 | The idea of this approach was to |
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77 | * build a custom break-out PCBA which can be slided into the EKSOS shelf (removing a subscriber line card) |
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78 | * build a ribbon cable with IDC connectors towards the EKSOS subscriber line card (DIN connector) and a 64pos 2-row header (break-out board) |
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80 | h4. break-out PCBA |
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82 | 6 | laforge | The boards has 16 RJ45 connectors. The center two pins (4+5) are routed to the first (left) IDC connector. The two surrounding pins (3+6) are routed to the second (right) IDC connector. This allows a single break-out board to carry either 16 or 32 subscriber ports. |
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84 | 5 | laforge | !20230811_120723.jpg! |
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86 | h4. ribbon cable with IDC connectors |
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88 | !20230811_120736.jpg! |
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90 | h4. break-out PCBA with IDC ribbon cable plugged in |
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92 | !20230811_120809.jpg! |
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94 | h4. subscriber line cards + breakout boards installed in rack |
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96 | !20230811_140854.jpg! |
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97 | 1 | laforge | |
98 | h2. icE1usb + Linux SBC |
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100 | Given that we needed multiple Ethernet ports in a Linux SBC with passive cooling, there weren't really all that many options on the market. I went for a *nanopi R5S*, which has 3 ethernet ports. |
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102 | h3. nanoPI R5S 12V DC re-work |
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104 | For some weird reason, the nanoPi R5S *only* supports USB-PD. There is no straight DC supply connector for feeding e.g. 12V to it. Not even an unpopulated header on the circuit board. |
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106 | This meant that it simply wouldn't power up at all if 12V were applied from the 12V mean-well power supply in the unit. Luckily, @tnt and I came up with some hardware re-work to modify the R5S to accept a 12V DC input without any USB-PD signaling: |
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108 | FIXME: Describe the rework |
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110 | h4. Unmodified R5S |
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112 | !20230809_233333.jpg! |
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114 | h4. R5S with removed resistor |
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116 | !20230809_233308.jpg! |
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118 | h4. R5S with additional pull-up resistor |
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120 | !20230809_233231.jpg! |