BAYCOM(9)

💖 BAYCOM(9) — the kernel reference guide, but make it cute 🎀

okay so this is the baycom page from the Kernel Reference Guide, and honestly? she's a whole vibe. amateur radio, kernel drivers, real hardware — the girls are coding. let's get into it ✨

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🌸 NAME 🌸

baycom — the amateur (AX.25) packet radio network driver for baycom modems 💅 like, she talks to your radio over packets, that's the whole thing, no cap.

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🦋 SYNOPSIS 🦋

#include <linux/baycom.h>
#include <linux/hdlcdrv.h>

that's it bestie, those two headers and you're in 🫶

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✨ DESCRIPTION ✨

so rn the driver supports three different modems: ser12, par96 and par97. three icons, one driver, she ate 🔥

🎀 ser12

this one is a very simple 1200 baud AFSK modem. lowkey a minimalist queen.

• the modem is literally just a modulator/demodulator chip — usually a TI TCM3105 🧚
• the computer is the one responsible for regenerating the receiver bit clock (yes, the PC is doing the work, main character energy fr)
• it connects to a serial port, hence the name ser12
• and here's the tea ☕: since the serial port is not used as an async serial port, the kernel driver for serial ports cannot be used. so this driver only supports standard serial hardware: 8250, 16450, 16550. that's the list, don't @ me

💜 par96

this one's a modem for 9600 baud FSK, compatible to the G3RUH standard. glow up.

• the modem does all the filtering and regenerates the receiver clock (she's independent 💅)
• data gets transferred from and to the PC via a shift register
• the shift register gets filled with 16 bits, and then an interrupt is signalled
• the PC then empties the shift register in a burst — iconic behaviour honestly
• this modem connects to the parallel port, hence the name par96 🌈

🍓 par97

this is a redesign of the par96 modem by Henning Rech, DF9IC. respect the icon 👑

• the modem is protocol compatible to par96
• but it uses only three low power ICs 🧚‍♀️
• and because of that it can be fed from the parallel port and does not require an additional power supply. sustainable queen, we stan 🌱

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👑 IOCTL CALLS 👑

the ioctl calls follow the implementation in the hdlcdrv. that's the vibe, that's the reference, go look there 💖

⭐ BAYCOMCTL_GETMODEMTYPE

returns the modem type (i.e. ser12 or par96) and the options in effect (currently only the source of the DCD signal). like a little vibe check for your modem 🔍

🌸 BAYCOMCTL_SETMODEMTYPE

sets the modem type and the options. Only superuser can do this — so yeah, you need the big permissions for this one, no shortcuts 🙈

🦋 BAYCOMCTL_GETDEBUG

returns some debugging values. Not always available — so don't come for her if it's not there, she's doing her best 😭

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💫 SEE ALSO 💫

baycom (9), soundmodem (9), linux/drivers/net/hdlcdrv.c,

(and yes the trailing comma is staying, it's part of the lore 💀)

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💜 AUTHOR 💜

baycom was written by Thomas Sailer, HB9JNX/AE4WA, (t.sailer@alumni.ethz.ch). thank you king, we appreciate you 🫶👑

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💡 friendly reminder bestie: this whole page is the kernel reference guide realness — if you're poking at hardware, double-check your serial chip situation before you go feral. ser12 only rolls with 8250, 16450, 16550 and that is not a suggestion 💅

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and that's the page!! this was Linux 2.1.x, dated 27 April 2008, filed under BAYCOM(9) — mwah, hope you understood it, ily, go build something cute with your packets 🎀💖✨🦋🌸