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| rnd:projects:aft [2022-12-25 22:04] – [SFP modules] asdf | rnd:projects:aft [2023-05-07 02:54] (current) – asdf |
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| SFP modules expose a great deal of data detailing their internal status, all accessible through I2C at one of two addresses (''0xA0'', ''0xA2''). Before data can be read, the EEPROM address must be loaded in by performing a dummy write containing the 8-bit EEPROM address to retrieve. For example, the device vendor name is stored in 16 bytes at I2C address ''0xA0'', EEPROM address 20. The following snippet demonstrates this procedure. | SFP modules expose a great deal of data detailing their internal status, all accessible through I2C at one of two addresses (''0xA0'', ''0xA2''). Before data can be read, the EEPROM address must be loaded in by performing a dummy write containing the 8-bit EEPROM address to retrieve. For example, the device vendor name is stored in 16 bytes at I2C address ''0xA0'', EEPROM address 20. The following snippet demonstrates this procedure. |
| |
| <code c> | <code cpp> |
| // load in the EEPROM address | // load in the EEPROM address |
| Wire.beginTransmission(0x50); | Wire.beginTransmission(0x50); |
| After each read, the internal address register is incremented so it points to the next byte. Given the way we're most likely to access this table, this fact is of relatively little use to us. | After each read, the internal address register is incremented so it points to the next byte. Given the way we're most likely to access this table, this fact is of relatively little use to us. |
| |
| | <table |tab_sfpreg_50> |
| | <caption>Registers of interest at I2C address 0x50</caption> |
| | |
| | <datatables paging="false"> |
| | ^ Value ^ Address (dec) ^ Data length ^ |
| | | Manufacturer name (ASCII) | 20 | 16 | |
| | | Compliance code | 3 | 8 | |
| | | Nominal signalling rate (100s Mbd) | 12 | 1 | |
| | | Supported optional DDM features | 93 | 1 | |
| | </datatables> |
| | </table> |
| | |
| | <table |tab_sfpreg_51> |
| | <caption>Registers of interest at I2C address 0x51</caption> |
| | |
| | <datatables paging="false"> |
| | ^ Value ^ Address (dec) ^ Data length ^ |
| | |
| | </datatables> |
| | </table> |
| ==== Serial data transmission ==== | ==== Serial data transmission ==== |
| |
| |
| ==== Communication ==== | ==== Communication ==== |
| UART communication testing is so far inconclusive---likely since the SFPs I've been using are of questionable status. | UART transmission is not looking terribly promising at this time. |
| |
| Interestingly, despite the testing module supposedly not supporting such functions, operations on ''0xa2'' appear to work as described in SFF-8472. | Different SFP models appear to produce different signals when the output is open. The SMF unit (unknown vendor) outputs nothing, while the Veloso units send (noisy) pulse trains (see {{ref>fig_idle}}). They also respond differently to inputs, with the former producing an inverted replica of the input and the latter outputting what might be PWM ({{ref>fig_k}}). |
| |
| | <figure center|fig_idle> |
| | <subfigure |fig_smf_idle> |
| | {{ :rnd:projects:smf-idle.png?400 |}} |
| | <caption>SMF</caption> |
| | </subfigure> |
| | <subfigure |fig_veloso_idle> |
| | {{ :rnd:projects:veloso-idle.png?400 |}} |
| | <caption>Veloso</caption> |
| | </subfigure> |
| | <caption>Idle responses from signal loopback</caption> |
| | </figure> |
| | |
| | <figure center|fig_k> |
| | <subfigure |fig_smf_k> |
| | {{ :rnd:projects:smf-k.png?400 |}} |
| | <caption>SMF</caption> |
| | </subfigure> |
| | <subfigure |fig_veloso_k> |
| | {{ :rnd:projects:veloso-k.png?400 |}} |
| | <caption>Veloso</caption> |
| | </subfigure> |
| | <caption>Responses to UART ''k'' at 115200 baud, 8N1</caption> |
| | </figure> |
| ==== Power considerations ==== | ==== Power considerations ==== |
| Portable operation is a must for this tester. | Portable operation is a must for this tester. |
| * [[https://github.com/Stutchbury/EncoderButton]] | * [[https://github.com/Stutchbury/EncoderButton]] |
| * [[https://www.instructables.com/Manchester-Code-Library-for-Arduino/]], [[https://github.com/mdeudon/Manchester]], [[wp>manchester code]] | * [[https://www.instructables.com/Manchester-Code-Library-for-Arduino/]], [[https://github.com/mdeudon/Manchester]], [[wp>manchester code]] |
| | * https://www.ti.com/lit/ug/tidu366/tidu366.pdf |
| | * https://cdn.hackaday.io/files/21599924091616/AN_2030_DDMI_for_SFP_Rev_E2.pdf |
| | * https://gitea.osmocom.org/electronics/osmo-small-hardware/raw/branch/master/sfp-breakout/sfp-experimenter.pdf |
| | * https://www.ti.com/lit/ds/symlink/sn65lvds1.pdf?ts=1672100269172&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FSN65LVDS1%252Fpart-details%252FSN65LVDS1D%253Futm_source%253Dgoogle%2526utm_medium%253Dcpc%2526utm_campaign%253Docb-tistore-promo-asc_opn_en-cpc-storeic-google-wwe%2526utm_content%253DDevice%2526ds_k%253DSN65LVDS1D%2526DCM%253Dyes%2526%2526utm_source%253Dgoogle%2526utm_medium%253Dcpc%2526utm_campaign%253D%2526utm_content%253D%2526ds_k%253Dsn65lvds1d%2526DCM%253Dyes%2526gclid%253DCjwKCAiAqaWdBhAvEiwAGAQltruYrSedpQ0uALxXlAq5xiuhmzbVhkdHlCKyi0L3cz9s1VCdN4uf8xoCVpwQAvD_BwE%2526gclsrc%253Daw.ds |
| | * https://hackaday.com/2020/05/11/new-teensy-4-1-arrives-with-100-mbps-ethernet-high-speed-usb-8-mb-flash/ |
| | * https://twitter.com/PA4DAN/status/1108517564005695491/photo/1 |
| | * https://www.fluxlight.com/content/Tech-Docs/AdTran%2012004800%20Datasheet.pdf |
| | * https://hackaday.com/2021/02/13/experiment-with-sfp-modules-with-this-handy-breakout/ |
| | |
| ===== References ===== | ===== References ===== |
| [(sparkfun_serialcomm>https://learn.sparkfun.com/tutorials/serial-communication)] | [(sparkfun_serialcomm>https://learn.sparkfun.com/tutorials/serial-communication)] |
| [(twi_protocol>https://ww1.microchip.com/downloads/en/devicedoc/doc0180.pdf)] | [(twi_protocol>https://ww1.microchip.com/downloads/en/devicedoc/doc0180.pdf)] |
| | |
| | {{tag>electronics}} |