2317: Pinouts
| Pinouts |
 Title text: The other side of USB-C is rotationally symmetric except that the 3rd pin from the top is designated FIREWIRE TRIBUTE PIN. |
Explanation
|
This explanation may be incomplete or incorrect: Created by a FIREWIRE TRIBUTE PIN. Should include a column for the actual purpose of the pin. Do NOT delete this tag too soon. If you can address this issue, please edit the page! Thanks. |
Electronics connecters are designed to transport both information and power. A pinout describes the function of each pin such as to communicate data, transport power, physical function (keying), etc. In this comic there is an absurd alternative to the actual pins used in connectors.
HDMI
| Label | Explanation |
|---|---|
| Data | Most digital communications cables contain at least one wire that carries data. Typically there will be a more descriptive name if there are multiple data pins. |
| +5V | Many actual pin configurations use +5 volts to supply power to a device. That's not what this means. |
| +6VI | V is usually used to represent volts, but here, VI represents the Roman numeral 6. |
| +7VII | V is usually used to represent volts, but here, VII represents the Roman numeral 7, continuing the pattern from above. |
| Antidata | Some ports use differential signaling, where a signal and its inverse are sent over a pair of pins (e.g. D+ and D-). This mixes that practice with a humorous reference to the notion of matter versus antimatter. There is no such thing as antidata. |
| Water | Labs often have ports connecting to common supplies of various supplying (Oxygen, water, fuel, vacuum). |
| Vacuum | Labs often have ports connecting to common supplies of various supplying (Oxygen, water, fuel, vacuum). |
| Amazon Copyright Pin | HDMI can optionally be protected by a digital rights management (DRM) scheme, known as HDCP. This pin humorously implies the presence of a different DRM scheme specific to Amazon.com. |
| Decorative | Decorative elements are pieces of an assembly that serve only an aesthetic purpose without any technical function. This would not be particularly useful inside a connector, as almost no one will ever see it. |
| +3.3V DC | As with the +5V pin, this could be used to supply power to a device. 3.3V is a typical voltage in digital electronics. |
| -3.3V DC | Negative voltages were used more frequently in the past, however modern systems typically generate any negative voltages they might require internally from the given positive voltages. |
| Tx | "Tx" typically refers to pins used to transmit as opposed to "Rx"/receive |
| Wx | "Wx" does not typically exist in the "Tx"/"Rx" scheme. In the weather forecasting community, Wx means "weather" . |
| Rx Only | "Rx" typically refers to pins used to receive as opposed to "Tx"/transmit. In this case "Rx" is used as part of a pun on "Rx (prescription) only" |
| Unknown | Occasionally extra pins will be included for future use, however they will typically be labeled "reserved" to point out that their usage is not yet defined. |
| +240V DC | High voltage DC is not typically used in small communications connectors. It would need to be low current to avoid generating excess heat. |
| 5V AC | Pins often supply low voltage direct current to devices. This pin supplies 5V alternating current, which is not typically supplied. |
| GND | GND typically refers to "ground" on pinout diagrams. |
| Ground | Compared to the above pin, this appears to be the same ground pin. However, the presence of both GND and Ground seems to imply that GND represents something other than the standard "ground" pin. Some systems have different grounds for analog and digital sections, but they would typically be disambiguated by terms like AGND. |
Micro USB
A ground pin is commonly found on USB and other pin connectors. At least one ground is necessary to complete the circuit, and some cables use multiple ground lines to distribute current or to support twisted pairs. However, there is no purpose served by having many more ground pins than data pins. Therefore, it seems rather silly for the micro USB to have 4 ground pins and only 1 functional "USB" pin. It also does not give much information about what the "USB" pin would do, as opposed to a standard pinout diagram. This diagram also leaves out the +5V power pin that is present in the real micro USB connector, which would render most USB peripherals unable to function.
The ordering and count of the pins may be an allusion to Monty Python's "Spam" sketch, in which one of the many Spam-related menu items is "Spam, Spam, Spam, egg, and Spam".
| Label | Explanation |
|---|---|
| GND | A ground pin |
| GND | A second ground pin |
| GND | A third ground pin |
| USB | Apparently the only data pin in this connector. |
| GND | A fourth ground pin. A real micro USB only has one ground pin. |
USB-C
| Label | Explanation |
|---|---|
| +5V DC | A common electronics supply voltage. |
| +3.3V DC | Another common electronics supply voltage. This pin is not present on USB type C, mostly because the voltage is too low to supply useful levels of power at the current limit of the pins. |
| +120V AC | Residential supply voltage in the United States; its use on an electronics connector would be very unusual, as it would burn out any unguarded transistor-logic electronics. |
| Boobytrap Pin (Pure Solder) | Solder is a metal alloy with a low melting temperature, used to bond electronic components together permanently. Making a connector pin out of it would likely result in the pin overheating and melting, thus bonding the connector to its receptacle, and thereby "trapping" the receptacle. |
| Mechanical | All connectors include portions whose job is to ensure a solid connection between the cable and the port. This is typically not the job of the pins, however. In real USB type C connectors, this task is performed by the center tongue of the female connector. |
| +3.3eV/C | Electron-volts per coulomb would be a very unusual unit to see in a pinout. It is equivalent to volts, however, so technically this pin would be a +3.3V pin. |
| Candlepin | Randall is making a pun on the word pin, which refers to a electrical connector pin as well as a thing to knock down in bowling. "candlepins" is a form of bowling. |
| Facebook use | This would imply that Facebook had a hand in specifying USB type C, and had a pin dedicated to their use. This would be strange given Facebook's primary business is web technology and would have little need for a dedicated pin in the USB standard. |
| +5V (Positrons) | Positrons are the antimatter counterparts to electrons. So this pin is supplying +5V, but does so by sourcing positrons into the device rather than sinking electrons out. NOTE: Positrons cannot be conducted through normal matter conductors as they would annihilate with the electrons. |
| Pin Roulette | Presumably in the same vein as "Chat Roulette", this pin's purpose is not rigidly defined and is instead left to chance. According to the title text, this pin's counterpart on the other side of the connector is the "FireWire Tribute Pin", so this cable would only be truly rotationally symmetric (which is the whole point of the USB-C connector) when the pin roulette ball lands on that same function. |
| GND | Ground pin. Typically denoted as "GND". |
| SKY | Reference to the ground pin, which refers to the common grounding on the larger metal body. There is no corresponding "sky" pin, although sky is often thought as the opposite of ground. |
| FIREWIRE TRIBUTE PIN | In Title text: Firewire is Apple's version of IEEE 1394 which is a 6 pin connector that has a ground pin a power pin and two pairs of data pins. How this pin is a tribute to firewire is unclear |
Coax
| Label | Explanation |
|---|---|
| Pin | A coax connector has two contacts - one pin, and the shield; typically the whole connector is labeled with whatever function/signal is carried by the pair. |
Transcript
- [Caption at top]
- Pinouts
- Quick Reference Guide
- [Four common connectors are depicted - vertically, rather than the usual horizontal orientation.]
- [The first connector is a 19-pin HDMI connector.]
- [The nine pins on the left are labeled:]
- Data
- +5V
- +6VI
- +7VII
- Antidata
- Water
- Vacuum
- Amazon Copyright Pin
- Decorative
- [The ten pins on the right are labeled:]
- +3.3V DC
- -3.3V DC
- Tx
- Wx
- Rx Only
- Unknown
- +240V DC
- 5V AC
- GND
- Ground
- [The second connector is a 5-pin Micro USB connector.]
- [The five pins are labeled:]
- GND
- GND
- GND
- USB
- GND
- [The third connector is a 24-pin USB-C connector, with only the right side labeled.]
- [The twelve pins on the right are labeled:]
- +5V DC
- +3.3V DC
- +120V AC
- Boobytrap Pin (Pure Solder)
- Mechanical
- +3.3eV/C
- Candlepin
- Facebook Use
- +5V (Positrons)
- Pin Roulette
- GND
- SKY
- [The fourth and final connector is a 1-pin COAX connector.]
- [The one pin in the center is labeled:]
- Pin
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refresh comments!Discussion
Can we add this one to a new category, "Comics that Randall makes just to screw with xkcd wiki contributors"? I can think of plenty of candidates for this category! Cosmogoblin (talk) 21:42, 8 June 2020 (UTC)
- Wouldn't be more useful to make a category for comics that Randall DOESN'T make to screw with xkcd wiki contributors? Might be smaller ... -- Hkmaly (talk) 22:26, 10 June 2020 (UTC)
The claim that a coax has only one conductive part is incorrect. It has two. The pin is the inner conductor. The shield is the outer conductor. Without both it wouldn't work.
- yes, but it's a "pin" out. Hence, "pin" WhiteDragon (talk) 21:37, 9 June 2020 (UTC)
I'd also say that the claim at the top that a pin can have only one bit or one voltage of power at a time is incorrect. Power over Ethernet is a perfect example of power and data at the same time. There are also plenty of types of signals which transmit multiple bits at once. A simple example would be a signal using four voltage levels to transmit two bits simultaneously, but there are many more fancy analog encodings that use phase and frequency and other characteristics to transmit data. Plus, you can often included two signals on the same conductors. For example, ADSL combined a normal phone signal and a higher frequency data signal on the same lines. Also cable TV combined many signals on one set of conductors.
So, anyway, I'd remove the claim. Mootstrap (talk) 23:00, 8 June 2020 (UTC)
- Just because it’s interesting: DCC with RailCom+ allows some cool stuff. It allows many-to-many high-power power transmission, robust many-to-many bidirectional data transmission, hot-swap with automatic configuration and collision resolution, physical position tracking of the connected devices, some way of short-circuit resolution with continued communication, mixing with other protocols, and all with only two pins, which may be arbitrarily interchanged at any time. Admittedly it has a much lower data rate than Power over Ethernet and terrible EMI, but potentially much higher power. 162.158.89.193 08:22, 9 June 2020 (UTC)
For that matter, the RF cable connecting a regular TV antenna, or the wire in a car that connects the radio antenna, carries the signals of all the channels.172.69.33.65 02:20, 9 June 2020 (UTC)
I think "Pin Roulette" is a pun on Penn Jillette, the talkative half of the Penn & Teller magic act, and maybe also a reference to chatroulette. Barmar (talk) 23:10, 8 June 2020 (UTC)
- Possible, but I'd stick with the simple explanation - that the "Pin Roulette" pin selects a random function when the connector's plugged in. 108.162.245.64 23:18, 8 June 2020 (UTC)
- Modern conectors additionally tend to have multi-purpose pins, which might be dangerous if you guess the current meaning of the pin wrong.Gunterkoenigsmann (talk) 06:15, 9 June 2020 (UTC)
In addition to pins being able to carry both data and power, or to carry multiple bits at a time, some pins function as clock signal pins that indicate bit boundaries rather than themselves carrying data; therefore I also think the claim should be either omitted or changed entirely. Vaedez (talk) 23:33, 8 June 2020 (UTC)
Firstly, no Soup? Secondly, GNDN might easily have been referenced. Thirdly, would a pin made of solder melt, as pins connected to wires/boards by solder do not melt the solder (under proper range of use). 141.101.107.158 23:38, 8 June 2020 (UTC)
- i think the implication is that it could melt, which is a trap--Vaedez (talk) 23:48, 8 June 2020 (UTC)
Perhaps we should add the actual usage of the pins to help those who actually want to know? 162.158.62.245 00:08, 9 June 2020 (UTC)
Wouldn't 3.3eV/C be a tiny fraction of 3.3V, since a columb is a much greater value of charge than that of the electron?--172.69.63.203 00:24, 9 June 2020 (UTC)
Depending on how you read it, the third pin from the top might match the 120V AC. This would make it a different kind of "tribute" to FireWire... EHusmark (talk) 07:52, 9 June 2020 (UTC)
- AFAIK FireWire allows many-to-many communication, while USB never did. The FireWire tribute pin could be a way to establish many-to-many communication. Alternatively, FireWire allows daisy-chaining, while USB supports only a tree network trough hubs. The FireWire pin could be somehow physically strange, so a second USB-C cable could be connected to it. 162.158.89.193 08:22, 9 June 2020 (UTC)
The "FireWire tribute pin" bit actually probably was intended to be about the 110V pin. Providing 110V is, of course, absurd, but FireWire was (I think) the first computer bus to use a relatively high bus voltage to send lots of power over the wire. The spec actually requires hardware to handle up to 30 VDC. In fact, I once heard lore about an early prototype PowerMac G4 (I think) that was nicknamed "FireBurner". Apple built it at one point in the distant past, and actually provided 30V worth of bus power. They didn't ship that configuration to the public as far as I know, but they used to make it available to companies who wanted to test their FireWire hardware for compatibility. Unfortunately, a lot of hardware manufacturers in the early days didn't pay attention to that 30V number and assumed that the hardware would always provide 12V like the Macs that had shipped up to that point. When they actually encountered 30V, a lot of those early devices didn't survive. Dgatwood (talk) 19:49, 6 August 2020 (UTC)
Added a little more description to the coax cable section, just in case it wasn't obvious to a layman what an example of the cable would be or why it was included with a cartoon about digital data cables.--172.69.68.195 22:46, 10 June 2020 (UTC)
