From 42f9ff08928b34c0f55b10cbfec6bcf5dff83fce Mon Sep 17 00:00:00 2001 From: Thorsten von Eicken Date: Wed, 12 Oct 2016 18:35:47 -0700 Subject: [PATCH] docs update --- README.md | 186 +----------------------------------------------------- 1 file changed, 3 insertions(+), 183 deletions(-) diff --git a/README.md b/README.md index 1521920..157f372 100644 --- a/README.md +++ b/README.md @@ -38,13 +38,12 @@ fork and added cool new features as well as bug fixes. ### Quick links In this document: [goals](#esp-link-goals), [uses](#esp-link-uses), [eye candy](#eye-candy), -[getting-started](#getting-started), [contact](#contact). +[getting-started](#getting-started), [serial-bridge](#serial-bridge), [contact](#contact). Separate documents: - [hardware configuration](FLASHING.md), [serial flashing](FLASHING.md#initial-serial-flashing) - [wifi configuration](WIFI-CONFIG.md) - [troubleshooting](TROUBLESHOOTING.md), [LED indicators](TROUBLESHOOTING.md#led-indicators) -- [serial bridge]() - [flashing an attached uC](UC-FLASHING.md) - [MQTT and outbound REST requests](RESTMQTT.md) - [service web pages](WEB-SERVER.md) @@ -148,8 +147,8 @@ From there, more advanced steps are: and forms - make changes or enhancements to esp-link and build your own firmware -Serial bridge and connections to Arduino, AVR, ARM, LPC microcontrollers ------------------------------------------------------------------------- +Serial bridge +------------- In order to connect through the esp-link to a microcontroller use port 23. For example, on linux you can use `nc esp-hostname 23` or `telnet esp-hostname 23`. @@ -158,185 +157,6 @@ Note that multiple connections to port 23 and 2323 can be made simultaneously. E intermix characters received on all these connections onto the serial TX and it will broadcast incoming characters from the serial RX to all connections. Use with caution! -### Flashing an attached AVR/Arduino - -There are three options for reprogramming an attached AVR/Arduino microcontroller: - -- Use avrdude and point it at port 23 of esp-link. Esp-link automatically detects the programming - sequence and issues a reset to the AVR. -- Use avrdude and point it at port 2323 of esp-link. This is the same as port 23 except that the - autodectection is not used and the reset happens because port 2323 is used -- Use curl or a similar tool to HTTP POST the firmware to esp-link. This uses the built-in - programmer, which only works for AVRs/Arduinos with the optiboot bootloader (which is std). - -To reprogram an Arduino / AVR microcontroller by pointing avrdude at port 23 or 2323 you -specify a serial port of the form `net:esp-link:23` in avrdude's -P option, where -`esp-link` is either the hostname of your esp-link or its IP address). -This is instead of specifying a serial port of the form /dev/ttyUSB0. -Esp-link detects that avrdude starts its connection with a flash synchronization sequence -and sends a reset to the AVR microcontroller so it can switch into flash programming mode. - -To reprogram using the HTTP POST method you need to first issue a POST to put optiboot into -programming mode: POST to `http://esp-link/pgm/sync`, this starts the process. Then check that -synchronization with optiboot has been achieved by issuing a GET to the same URL -(`http://esp-link/pgm/sync`). Repeat until you have sync (takes <500ms normally). Finally -issue a POST request to `http://esp-link/pgm/upload` with your hex file as POST data (raw, -not url-encoded or multipart-mime. Please look into the avrflash script for the curl command-line -details or use that script directly (`./avrflash esp-link.local my_sketch.hex`). -_Important_: after the initial sync request that resets the AVR you have 10 seconds to get to the -upload post or esp-link will time-out. So if you're manually entering curl commands have them -prepared so you can copy&paste! - -Beware of the baud rate, which you can set on the uC Console page. Sometimes you may be using -115200 baud in sketches but the bootloader may use 57600 baud. When you use port 23 or 2323 you -need to set the baud rate correctly. If you use the built-in programmer (HTTP POST method) then -esp-link will try the configured baud rate and also 9600, 57600, and 115200 baud, so it should -work even if you have the wrong baud rate configured... - -When to use which method? If port 23 works then go with that. If you have trouble getting sync -or it craps out in the middle too often then try the built-in programmer with the HTTP POST. -If your AVR doesn't use optiboot then use port 2323 since esp-link may not recognize the programming -sequence and not issue a reset if you use port 23. - -If you are having trouble with the built-in programmer and see something like this: - -``` -# ./avrflash 192.168.3.104 blink.hex -Error checking sync: FAILED to SYNC: abandoned after timeout, got: -:\xF/\x00\xCj\xCz\xCJ\xCZ\xC\xAÜ\xC\xAä\xC\xAÜ\xC\xAä\xC\xBì\xC\xBô\xC\xBì\xC\xBô\xC\xAÜ\xC\xAä\xC -``` - -the most likely cause is a baud rate mismatch and/or a bad connection from the esp8266 to the -AVRs reset line. -The baud rate used by esp-link is set on the uC Console web page and, as mentioned above, it will -automatically try 9600, 57600, and 115200 as well. -The above garbage characters are most likely due to optiboot timing out and starting the sketch -and then the sketch sending data at a different baud rate than configured into esp-link. -Note that sketches don't necessarily use the same baud rate as optiboot, so you may have the -correct baud rate configured but reset isn't functioning, or reset may be functioning but the -baud rate may be incorrect. - -The output of a successful flash using the built-in programmer looks like this: - -``` -Success. 3098 bytes at 57600 baud in 0.8s, 3674B/s 63% efficient -``` - -This says that the sketch comprises 3098 bytes of flash, was written in 0.8 seconds -(excludes the initial sync time) at 57600 baud, -and the 3098 bytes were flashed at a rate of 3674 bytes per second. -The efficiency measure is the ratio of the actual rate to the serial baud rate, -thus 3674/5760 = 0.63 (there are 10 baud per character). -The efficiency is not 100% because there is protocol overhead (such as sync, record type, and -length characters) -and there is dead time waiting for an ack or preparing the next record to be sent. - -### Details of built-in AVR flash algorithm - -The built-in flashing algorithm differs a bit from what avrdude does. The programming protocol -states that STK_GET_SYNC+CRC_EOP (0x30 0x20) should be sent to synchronize, but that works poorly -because the AVR's UART only buffers one character. This means that if STK_GET_SYNC+CRC_EOP is -sent twice there is a high chance that only the last character (CRC_EOP) is actually -received. If that is followed by another STK_GET_SYNC+CRC_EOP sequence then optiboot receives -CRC_EOP+STK_GET_SYNC+CRC_EOP which causes it to abort and run the old sketch. Ending up in that -situation is quite likely because optiboot initializes the UART as one of the first things, but -then goes off an flashes an LED for ~300ms during which it doesn't empty the UART. - -Looking at the optiboot code, the good news is that CRC_EOP+CRC_EOP can be used to get an initial -response without the overrun danger of the normal sync sequence and this is what esp-link does. -The programming sequence runs as follows: - -- esp-link sends a brief reset pulse (1ms) -- esp-link sends CRC_EOP+CRC_EOP ~50ms later -- esp-link sends CRC_EOP+CRC_EOP every ~70-80ms -- eventually optiboot responds with STK_INSYNC+STK_OK (0x14;0x10) -- esp-link sends one CRC_EOP to sort out the even/odd issue -- either optiboot responds with STK_INSYNC+STK_OK or nothing happens for 70-80ms, in which case - esp-link sends another CRC_EOP -- esp-link sends STK_GET_SYNC+CRC_EOP and optiboot responds with STK_INSYNC+STK_OK and we're in - sync now -- esp-link sends the next command (starts with 'u') and programming starts... - -If no sync is achieved, esp-link changes baud rate and the whole thing starts over with a reset -pulse about 600ms, esp-link gives up after about 5 seconds and reports an error. - -### Flashing an attached ARM processor - -You can reprogram NXP's LPC800-series and many other ARM processors as well by pointing your -programmer similarly at the esp-link's port 23. For example, if you are using -https://github.com/jeelabs/embello/tree/master/tools/uploader a command line like -`uploader -t -s -w esp-link:23 build/firmware.bin` does the trick. -The way it works is that the uploader uses telnet protocol escape sequences in order to -make esp-link issue the appropriate "ISP" and reset sequence to the microcontroller to start the -flash programming. If you use a different ARM programming tool it will work as well as long as -it starts the connection with the `?\r\n` synchronization sequence. - -### Flashing an attached esp8266 - -Yes, you can use esp-link running on one esp8266 module to flash another esp8266 module, -however it is rather tricky! The problem is not electric, it is wifi interference. -The basic idea is to use some method to direct the esp8266 flash program to port 2323 of -esp-link. Using port 2323 with the appropriate wiring will cause the esp8266's reset and -gpio0 pins to be toggled such that the chip enters the flash programming mode. - -One option for connecting the programmer with esp-link is to use my version of esptool.py -at http://github.com/tve/esptool, which supports specifying a URL instead of a port. Thus -instead of specifying something like `--port /dev/ttyUSB0` or `--port COM1` you specify -`--port socket://esp-link.local:2323`. Important: the baud rate specified on the esptool.py -command-line is irrelevant as the baud rate used by esp-link will be the one set in the -uC console page. Fortunately the esp8266 bootloader does auto-baud detection. (Setting the -baud rate to 115200 is recommended.) - -Another option is to use a serial-to-tcp port forwarding driver and point that to port 2323 -of esp-link. On windows users have reported success with -[HW Virtual Serial Port](http://www.hw-group.com/products/hw_vsp/hw_vsp2_en.html) - -Now to the interference problem: once the attached esp8266 is reset it -starts outputting its 26Mhz clock on gpio0, which needs to be attached to -the esp8266 running esp-link (since it needs to drive gpio0 low during -the reset to enter flash mode). This 26Mhz signal on gpio0 causes a -significant amount of radio interference with the result that the esp8266 -running esp-link has trouble receiving Wifi packets. You can observe this -by running a ping to esp-link in another window: as soon as the target -esp8266 is reset, the pings become very slow or stop altogetehr. As soon -as you remove power to the attached esp8266 the pings resume beautifully. - -To try and get the interference under control, try some of the following: -add a series 100ohm resistor and 100pf capacitor to ground as close to -the gpio0 pin as possible (basically a low pass filter); and/or pass -the cable connecting the two esp8266's through a ferrite bead. - -### Debug log - -The esp-link web UI can display the esp-link debug log (os_printf statements in the code). This -is handy but sometimes not sufficient. Esp-link also prints the debug info to the UART where -it is sometimes more convenient and sometimes less... For this reason three UART debug log -modes are supported that can be set in the web UI (and the mode is saved in flash): - -- auto: the UART log starts enabled at boot using uart0 and disables itself when esp-link - associates with an AP. It re-enables itself if the association is lost. -- off: the UART log is always off -- on0: the UART log is always on using uart0 -- on1: the UART log is always on using uart1 (gpio2 pin) - -Note that even if the UART log is always off the ROM prints to uart0 whenever the -esp8266 comes out of reset. This cannot be disabled. - -Outbound HTTP REST requests and MQTT client -------------------------------------------- - -The V2 versions of esp-link use the SLIP protocol over the serial link to support simple outbound -HTTP REST requests as well as an MQTT client. The SLIP protocol consists of commands with -binary arguments sent from the -attached microcontroller to the esp8266, which then performs the command and responds back. -The responses back use a callback address in the attached microcontroller code, i.e., the -command sent by the uC contains a callback address and the response from the esp8266 starts -with that callback address. This enables asynchronous communication where esp-link can notify the -uC when requests complete or when other actions happen, such as wifi connectivity status changes. - -You can find REST and MQTT libraries as well as demo sketches in the -[el-client](https://github.com/jeelabs/el-client) repository. - Contact -------