1.. SPDX-License-Identifier: GPL-2.0 2.. include:: <isonum.txt> 3 4========================================================= 5SCC.C - Linux driver for Z8530 based HDLC cards for AX.25 6========================================================= 7 8 9This is a subset of the documentation. To use this driver you MUST have the 10full package from: 11 12Internet: 13 14 1. ftp://ftp.ccac.rwth-aachen.de/pub/jr/z8530drv-utils_3.0-3.tar.gz 15 16 2. ftp://ftp.pspt.fi/pub/ham/linux/ax25/z8530drv-utils_3.0-3.tar.gz 17 18Please note that the information in this document may be hopelessly outdated. 19A new version of the documentation, along with links to other important 20Linux Kernel AX.25 documentation and programs, is available on 21http://yaina.de/jreuter 22 23Copyright |copy| 1993,2000 by Joerg Reuter DL1BKE <jreuter@yaina.de> 24 25portions Copyright |copy| 1993 Guido ten Dolle PE1NNZ 26 27for the complete copyright notice see >> Copying.Z8530DRV << 28 291. Initialization of the driver 30=============================== 31 32To use the driver, 3 steps must be performed: 33 34 1. if compiled as module: loading the module 35 2. Setup of hardware, MODEM and KISS parameters with sccinit 36 3. Attach each channel to the Linux kernel AX.25 with "ifconfig" 37 38Unlike the versions below 2.4 this driver is a real network device 39driver. If you want to run xNOS instead of our fine kernel AX.25 40use a 2.x version (available from above sites) or read the 41AX.25-HOWTO on how to emulate a KISS TNC on network device drivers. 42 43 441.1 Loading the module 45====================== 46 47(If you're going to compile the driver as a part of the kernel image, 48 skip this chapter and continue with 1.2) 49 50Before you can use a module, you'll have to load it with:: 51 52 insmod scc.o 53 54please read 'man insmod' that comes with module-init-tools. 55 56You should include the insmod in one of the /etc/rc.d/rc.* files, 57and don't forget to insert a call of sccinit after that. It 58will read your /etc/z8530drv.conf. 59 601.2. /etc/z8530drv.conf 61======================= 62 63To setup all parameters you must run /sbin/sccinit from one 64of your rc.*-files. This has to be done BEFORE you can 65"ifconfig" an interface. Sccinit reads the file /etc/z8530drv.conf 66and sets the hardware, MODEM and KISS parameters. A sample file is 67delivered with this package. Change it to your needs. 68 69The file itself consists of two main sections. 70 711.2.1 configuration of hardware parameters 72========================================== 73 74The hardware setup section defines the following parameters for each 75Z8530:: 76 77 chip 1 78 data_a 0x300 # data port A 79 ctrl_a 0x304 # control port A 80 data_b 0x301 # data port B 81 ctrl_b 0x305 # control port B 82 irq 5 # IRQ No. 5 83 pclock 4915200 # clock 84 board BAYCOM # hardware type 85 escc no # enhanced SCC chip? (8580/85180/85280) 86 vector 0 # latch for interrupt vector 87 special no # address of special function register 88 option 0 # option to set via sfr 89 90 91chip 92 - this is just a delimiter to make sccinit a bit simpler to 93 program. A parameter has no effect. 94 95data_a 96 - the address of the data port A of this Z8530 (needed) 97ctrl_a 98 - the address of the control port A (needed) 99data_b 100 - the address of the data port B (needed) 101ctrl_b 102 - the address of the control port B (needed) 103 104irq 105 - the used IRQ for this chip. Different chips can use different 106 IRQs or the same. If they share an interrupt, it needs to be 107 specified within one chip-definition only. 108 109pclock - the clock at the PCLK pin of the Z8530 (option, 4915200 is 110 default), measured in Hertz 111 112board 113 - the "type" of the board: 114 115 ======================= ======== 116 SCC type value 117 ======================= ======== 118 PA0HZP SCC card PA0HZP 119 EAGLE card EAGLE 120 PC100 card PC100 121 PRIMUS-PC (DG9BL) card PRIMUS 122 BayCom (U)SCC card BAYCOM 123 ======================= ======== 124 125escc 126 - if you want support for ESCC chips (8580, 85180, 85280), set 127 this to "yes" (option, defaults to "no") 128 129vector 130 - address of the vector latch (aka "intack port") for PA0HZP 131 cards. There can be only one vector latch for all chips! 132 (option, defaults to 0) 133 134special 135 - address of the special function register on several cards. 136 (option, defaults to 0) 137 138option - The value you write into that register (option, default is 0) 139 140You can specify up to four chips (8 channels). If this is not enough, 141just change:: 142 143 #define MAXSCC 4 144 145to a higher value. 146 147Example for the BAYCOM USCC: 148---------------------------- 149 150:: 151 152 chip 1 153 data_a 0x300 # data port A 154 ctrl_a 0x304 # control port A 155 data_b 0x301 # data port B 156 ctrl_b 0x305 # control port B 157 irq 5 # IRQ No. 5 (#) 158 board BAYCOM # hardware type (*) 159 # 160 # SCC chip 2 161 # 162 chip 2 163 data_a 0x302 164 ctrl_a 0x306 165 data_b 0x303 166 ctrl_b 0x307 167 board BAYCOM 168 169An example for a PA0HZP card: 170----------------------------- 171 172:: 173 174 chip 1 175 data_a 0x153 176 data_b 0x151 177 ctrl_a 0x152 178 ctrl_b 0x150 179 irq 9 180 pclock 4915200 181 board PA0HZP 182 vector 0x168 183 escc no 184 # 185 # 186 # 187 chip 2 188 data_a 0x157 189 data_b 0x155 190 ctrl_a 0x156 191 ctrl_b 0x154 192 irq 9 193 pclock 4915200 194 board PA0HZP 195 vector 0x168 196 escc no 197 198A DRSI would should probably work with this: 199-------------------------------------------- 200(actually: two DRSI cards...) 201 202:: 203 204 chip 1 205 data_a 0x303 206 data_b 0x301 207 ctrl_a 0x302 208 ctrl_b 0x300 209 irq 7 210 pclock 4915200 211 board DRSI 212 escc no 213 # 214 # 215 # 216 chip 2 217 data_a 0x313 218 data_b 0x311 219 ctrl_a 0x312 220 ctrl_b 0x310 221 irq 7 222 pclock 4915200 223 board DRSI 224 escc no 225 226Note that you cannot use the on-board baudrate generator off DRSI 227cards. Use "mode dpll" for clock source (see below). 228 229This is based on information provided by Mike Bilow (and verified 230by Paul Helay) 231 232The utility "gencfg" 233-------------------- 234 235If you only know the parameters for the PE1CHL driver for DOS, 236run gencfg. It will generate the correct port addresses (I hope). 237Its parameters are exactly the same as the ones you use with 238the "attach scc" command in net, except that the string "init" must 239not appear. Example:: 240 241 gencfg 2 0x150 4 2 0 1 0x168 9 4915200 242 243will print a skeleton z8530drv.conf for the OptoSCC to stdout. 244 245:: 246 247 gencfg 2 0x300 2 4 5 -4 0 7 4915200 0x10 248 249does the same for the BAYCOM USCC card. In my opinion it is much easier 250to edit scc_config.h... 251 252 2531.2.2 channel configuration 254=========================== 255 256The channel definition is divided into three sub sections for each 257channel: 258 259An example for scc0:: 260 261 # DEVICE 262 263 device scc0 # the device for the following params 264 265 # MODEM / BUFFERS 266 267 speed 1200 # the default baudrate 268 clock dpll # clock source: 269 # dpll = normal half duplex operation 270 # external = MODEM provides own Rx/Tx clock 271 # divider = use full duplex divider if 272 # installed (1) 273 mode nrzi # HDLC encoding mode 274 # nrzi = 1k2 MODEM, G3RUH 9k6 MODEM 275 # nrz = DF9IC 9k6 MODEM 276 # 277 bufsize 384 # size of buffers. Note that this must include 278 # the AX.25 header, not only the data field! 279 # (optional, defaults to 384) 280 281 # KISS (Layer 1) 282 283 txdelay 36 # (see chapter 1.4) 284 persist 64 285 slot 8 286 tail 8 287 fulldup 0 288 wait 12 289 min 3 290 maxkey 7 291 idle 3 292 maxdef 120 293 group 0 294 txoff off 295 softdcd on 296 slip off 297 298The order WITHIN these sections is unimportant. The order OF these 299sections IS important. The MODEM parameters are set with the first 300recognized KISS parameter... 301 302Please note that you can initialize the board only once after boot 303(or insmod). You can change all parameters but "mode" and "clock" 304later with the Sccparam program or through KISS. Just to avoid 305security holes... 306 307(1) this divider is usually mounted on the SCC-PBC (PA0HZP) or not 308 present at all (BayCom). It feeds back the output of the DPLL 309 (digital pll) as transmit clock. Using this mode without a divider 310 installed will normally result in keying the transceiver until 311 maxkey expires --- of course without sending anything (useful). 312 3132. Attachment of a channel by your AX.25 software 314================================================= 315 3162.1 Kernel AX.25 317================ 318 319To set up an AX.25 device you can simply type:: 320 321 ifconfig scc0 44.128.1.1 hw ax25 dl0tha-7 322 323This will create a network interface with the IP number 44.128.20.107 324and the callsign "dl0tha". If you do not have any IP number (yet) you 325can use any of the 44.128.0.0 network. Note that you do not need 326axattach. The purpose of axattach (like slattach) is to create a KISS 327network device linked to a TTY. Please read the documentation of the 328ax25-utils and the AX.25-HOWTO to learn how to set the parameters of 329the kernel AX.25. 330 3312.2 NOS, NET and TFKISS 332======================= 333 334Since the TTY driver (aka KISS TNC emulation) is gone you need 335to emulate the old behaviour. The cost of using these programs is 336that you probably need to compile the kernel AX.25, regardless of whether 337you actually use it or not. First setup your /etc/ax25/axports, 338for example:: 339 340 9k6 dl0tha-9 9600 255 4 9600 baud port (scc3) 341 axlink dl0tha-15 38400 255 4 Link to NOS 342 343Now "ifconfig" the scc device:: 344 345 ifconfig scc3 44.128.1.1 hw ax25 dl0tha-9 346 347You can now axattach a pseudo-TTY:: 348 349 axattach /dev/ptys0 axlink 350 351and start your NOS and attach /dev/ptys0 there. The problem is that 352NOS is reachable only via digipeating through the kernel AX.25 353(disastrous on a DAMA controlled channel). To solve this problem, 354configure "rxecho" to echo the incoming frames from "9k6" to "axlink" 355and outgoing frames from "axlink" to "9k6" and start:: 356 357 rxecho 358 359Or simply use "kissbridge" coming with z8530drv-utils:: 360 361 ifconfig scc3 hw ax25 dl0tha-9 362 kissbridge scc3 /dev/ptys0 363 364 3653. Adjustment and Display of parameters 366======================================= 367 3683.1 Displaying SCC Parameters: 369============================== 370 371Once a SCC channel has been attached, the parameter settings and 372some statistic information can be shown using the param program:: 373 374 dl1bke-u:~$ sccstat scc0 375 376 Parameters: 377 378 speed : 1200 baud 379 txdelay : 36 380 persist : 255 381 slottime : 0 382 txtail : 8 383 fulldup : 1 384 waittime : 12 385 mintime : 3 sec 386 maxkeyup : 7 sec 387 idletime : 3 sec 388 maxdefer : 120 sec 389 group : 0x00 390 txoff : off 391 softdcd : on 392 SLIP : off 393 394 Status: 395 396 HDLC Z8530 Interrupts Buffers 397 ----------------------------------------------------------------------- 398 Sent : 273 RxOver : 0 RxInts : 125074 Size : 384 399 Received : 1095 TxUnder: 0 TxInts : 4684 NoSpace : 0 400 RxErrors : 1591 ExInts : 11776 401 TxErrors : 0 SpInts : 1503 402 Tx State : idle 403 404 405The status info shown is: 406 407============== ============================================================== 408Sent number of frames transmitted 409Received number of frames received 410RxErrors number of receive errors (CRC, ABORT) 411TxErrors number of discarded Tx frames (due to various reasons) 412Tx State status of the Tx interrupt handler: idle/busy/active/tail (2) 413RxOver number of receiver overruns 414TxUnder number of transmitter underruns 415RxInts number of receiver interrupts 416TxInts number of transmitter interrupts 417EpInts number of receiver special condition interrupts 418SpInts number of external/status interrupts 419Size maximum size of an AX.25 frame (*with* AX.25 headers!) 420NoSpace number of times a buffer could not get allocated 421============== ============================================================== 422 423An overrun is abnormal. If lots of these occur, the product of 424baudrate and number of interfaces is too high for the processing 425power of your computer. NoSpace errors are unlikely to be caused by the 426driver or the kernel AX.25. 427 428 4293.2 Setting Parameters 430====================== 431 432 433The setting of parameters of the emulated KISS TNC is done in the 434same way in the SCC driver. You can change parameters by using 435the kissparms program from the ax25-utils package or use the program 436"sccparam":: 437 438 sccparam <device> <paramname> <decimal-|hexadecimal value> 439 440You can change the following parameters: 441 442=========== ===== 443param value 444=========== ===== 445speed 1200 446txdelay 36 447persist 255 448slottime 0 449txtail 8 450fulldup 1 451waittime 12 452mintime 3 453maxkeyup 7 454idletime 3 455maxdefer 120 456group 0x00 457txoff off 458softdcd on 459SLIP off 460=========== ===== 461 462 463The parameters have the following meaning: 464 465speed: 466 The baudrate on this channel in bits/sec 467 468 Example: sccparam /dev/scc3 speed 9600 469 470txdelay: 471 The delay (in units of 10 ms) after keying of the 472 transmitter, until the first byte is sent. This is usually 473 called "TXDELAY" in a TNC. When 0 is specified, the driver 474 will just wait until the CTS signal is asserted. This 475 assumes the presence of a timer or other circuitry in the 476 MODEM and/or transmitter, that asserts CTS when the 477 transmitter is ready for data. 478 A normal value of this parameter is 30-36. 479 480 Example: sccparam /dev/scc0 txd 20 481 482persist: 483 This is the probability that the transmitter will be keyed 484 when the channel is found to be free. It is a value from 0 485 to 255, and the probability is (value+1)/256. The value 486 should be somewhere near 50-60, and should be lowered when 487 the channel is used more heavily. 488 489 Example: sccparam /dev/scc2 persist 20 490 491slottime: 492 This is the time between samples of the channel. It is 493 expressed in units of 10 ms. About 200-300 ms (value 20-30) 494 seems to be a good value. 495 496 Example: sccparam /dev/scc0 slot 20 497 498tail: 499 The time the transmitter will remain keyed after the last 500 byte of a packet has been transferred to the SCC. This is 501 necessary because the CRC and a flag still have to leave the 502 SCC before the transmitter is keyed down. The value depends 503 on the baudrate selected. A few character times should be 504 sufficient, e.g. 40ms at 1200 baud. (value 4) 505 The value of this parameter is in 10 ms units. 506 507 Example: sccparam /dev/scc2 4 508 509full: 510 The full-duplex mode switch. This can be one of the following 511 values: 512 513 0: The interface will operate in CSMA mode (the normal 514 half-duplex packet radio operation) 515 1: Fullduplex mode, i.e. the transmitter will be keyed at 516 any time, without checking the received carrier. It 517 will be unkeyed when there are no packets to be sent. 518 2: Like 1, but the transmitter will remain keyed, also 519 when there are no packets to be sent. Flags will be 520 sent in that case, until a timeout (parameter 10) 521 occurs. 522 523 Example: sccparam /dev/scc0 fulldup off 524 525wait: 526 The initial waittime before any transmit attempt, after the 527 frame has been queue for transmit. This is the length of 528 the first slot in CSMA mode. In full duplex modes it is 529 set to 0 for maximum performance. 530 The value of this parameter is in 10 ms units. 531 532 Example: sccparam /dev/scc1 wait 4 533 534maxkey: 535 The maximal time the transmitter will be keyed to send 536 packets, in seconds. This can be useful on busy CSMA 537 channels, to avoid "getting a bad reputation" when you are 538 generating a lot of traffic. After the specified time has 539 elapsed, no new frame will be started. Instead, the trans- 540 mitter will be switched off for a specified time (parameter 541 min), and then the selected algorithm for keyup will be 542 started again. 543 The value 0 as well as "off" will disable this feature, 544 and allow infinite transmission time. 545 546 Example: sccparam /dev/scc0 maxk 20 547 548min: 549 This is the time the transmitter will be switched off when 550 the maximum transmission time is exceeded. 551 552 Example: sccparam /dev/scc3 min 10 553 554idle: 555 This parameter specifies the maximum idle time in full duplex 556 2 mode, in seconds. When no frames have been sent for this 557 time, the transmitter will be keyed down. A value of 0 is 558 has same result as the fullduplex mode 1. This parameter 559 can be disabled. 560 561 Example: sccparam /dev/scc2 idle off # transmit forever 562 563maxdefer 564 This is the maximum time (in seconds) to wait for a free channel 565 to send. When this timer expires the transmitter will be keyed 566 IMMEDIATELY. If you love to get trouble with other users you 567 should set this to a very low value ;-) 568 569 Example: sccparam /dev/scc0 maxdefer 240 # 2 minutes 570 571 572txoff: 573 When this parameter has the value 0, the transmission of packets 574 is enable. Otherwise it is disabled. 575 576 Example: sccparam /dev/scc2 txoff on 577 578group: 579 It is possible to build special radio equipment to use more than 580 one frequency on the same band, e.g. using several receivers and 581 only one transmitter that can be switched between frequencies. 582 Also, you can connect several radios that are active on the same 583 band. In these cases, it is not possible, or not a good idea, to 584 transmit on more than one frequency. The SCC driver provides a 585 method to lock transmitters on different interfaces, using the 586 "param <interface> group <x>" command. This will only work when 587 you are using CSMA mode (parameter full = 0). 588 589 The number <x> must be 0 if you want no group restrictions, and 590 can be computed as follows to create restricted groups: 591 <x> is the sum of some OCTAL numbers: 592 593 594 === ======================================================= 595 200 This transmitter will only be keyed when all other 596 transmitters in the group are off. 597 100 This transmitter will only be keyed when the carrier 598 detect of all other interfaces in the group is off. 599 0xx A byte that can be used to define different groups. 600 Interfaces are in the same group, when the logical AND 601 between their xx values is nonzero. 602 === ======================================================= 603 604 Examples: 605 606 When 2 interfaces use group 201, their transmitters will never be 607 keyed at the same time. 608 609 When 2 interfaces use group 101, the transmitters will only key 610 when both channels are clear at the same time. When group 301, 611 the transmitters will not be keyed at the same time. 612 613 Don't forget to convert the octal numbers into decimal before 614 you set the parameter. 615 616 Example: (to be written) 617 618softdcd: 619 use a software dcd instead of the real one... Useful for a very 620 slow squelch. 621 622 Example: sccparam /dev/scc0 soft on 623 624 6254. Problems 626=========== 627 628If you have tx-problems with your BayCom USCC card please check 629the manufacturer of the 8530. SGS chips have a slightly 630different timing. Try Zilog... A solution is to write to register 8 631instead to the data port, but this won't work with the ESCC chips. 632*SIGH!* 633 634A very common problem is that the PTT locks until the maxkeyup timer 635expires, although interrupts and clock source are correct. In most 636cases compiling the driver with CONFIG_SCC_DELAY (set with 637make config) solves the problems. For more hints read the (pseudo) FAQ 638and the documentation coming with z8530drv-utils. 639 640I got reports that the driver has problems on some 386-based systems. 641(i.e. Amstrad) Those systems have a bogus AT bus timing which will 642lead to delayed answers on interrupts. You can recognize these 643problems by looking at the output of Sccstat for the suspected 644port. If it shows under- and overruns you own such a system. 645 646Delayed processing of received data: This depends on 647 648- the kernel version 649 650- kernel profiling compiled or not 651 652- a high interrupt load 653 654- a high load of the machine --- running X, Xmorph, XV and Povray, 655 while compiling the kernel... hmm ... even with 32 MB RAM ... ;-) 656 Or running a named for the whole .ampr.org domain on an 8 MB 657 box... 658 659- using information from rxecho or kissbridge. 660 661Kernel panics: please read /linux/README and find out if it 662really occurred within the scc driver. 663 664If you cannot solve a problem, send me 665 666- a description of the problem, 667- information on your hardware (computer system, scc board, modem) 668- your kernel version 669- the output of cat /proc/net/z8530 670 6714. Thor RLC100 672============== 673 674Mysteriously this board seems not to work with the driver. Anyone 675got it up-and-running? 676 677 678Many thanks to Linus Torvalds and Alan Cox for including the driver 679in the Linux standard distribution and their support. 680 681:: 682 683 Joerg Reuter ampr-net: dl1bke@db0pra.ampr.org 684 AX-25 : DL1BKE @ DB0ABH.#BAY.DEU.EU 685 Internet: jreuter@yaina.de 686 WWW : http://yaina.de/jreuter 687