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diff --git a/posts/2013-12-09-wavedrum-connectors.markdown b/posts/2013-12-09-wavedrum-connectors.markdown deleted file mode 100644 index ab03368..0000000 --- a/posts/2013-12-09-wavedrum-connectors.markdown +++ /dev/null @@ -1,135 +0,0 @@ ---- -title: Connectors on the Wavedrum's circuit board -tags: DIY,electronics,music,hacking,wavedrum ---- - -On the circuit board of the Wavedrum there are solder holes to -accomodate three large connectors. Since they are so easily -accessible and thus very inviting to anyone interested in modifying -the instrument, I decided to trace each of the pins to its -destination. - -The three connectors are named CN10, CN11, and CN12, respectively. -CN10 is found on the bottom right, CN11 on the bottom left, and CN12 -close to the left edge below the micro SD card reader. - -<img class="full stretch" src="/images/posts/2013/wavedrum-connectors.jpg" alt="connectors on the mainboard" /> - -# CN10: digital audio interface - -Most of the ten pins of CN10 are outputs. The first three pins carry -clock signals used by the analogue to digital and digital to analogue -converters on the top-side of the board. Pin four gives access to the -PDN (power down) signal which is used to disable the converters. The -next three pins are connected over the resistors R85, R84, and R83 to -the DSP's pins 145, 144, and 143 (respectively); according to the -[DSP's datasheet](http://www.analog.com/static/imported-files/data_sheets/ADSP-21371_21375.pdf) -these pins are `DAI_P8` (`SFSI`), `DAI_P10` (`SD2B`), and `DAI_P11` -(`SD3A`), and are thus part of the Digital Audio Interface (DAI). The -remaining three pins on CN10 expose the supply voltage, ground, and an -alternative positive voltage (the same as on the plus pole of the -silver capacitors near the right edge of the board). These are the -signals left to right: - - . | direction | description ----|-----------|----------------- - 1 | output | Master clock - 2 | output | Audio serial clock - 3 | output | Left/right clock - 4 | output | `PDN` (power down) - 5 | input? | `DAI_P8` / `SFSI` - 6 | input? | `DAI_P10` / `SD2B` - 7 | input? | `DAI_P11` / `SD3A` - 8 | output | V_A, or V_DD - 9 | output | GND -10 | output | alternative positive voltage - -What is this all good for? Well, since all these clocks and voltages -are exported it becomes relatively easy to connect an external digital -to analogue converter (when `DAI_P8`, `DAI_P10`, and `DAI_P11` are -used as outputs), or an external analogue to digital converter (if the -DSP pins are used as inputs instead). As there are protective -resistors between the DSP pins and the connector pins 5--7 I assume -that they are supposed to be used as inputs. - - -# CN11: JTAG interface - -Moving on to the left bottom edge of the board we see a 14-pin -connector with the name CN11. This connector gives access to the JTAG -interface on the DSP, which allows system debugging. Unfortunately, I -don't own a JTAG dongle and the free JTAG debugger -[OpenOCD](http://openocd.sourceforge.net) does not support the SHARC -core, so I haven't been able to experiment with the debugging -interface. I'm not sure whether it is possible to use debugging -feature without hardware/software provided by Analog Devices. Using -JTAG it should be possible to overwrite the flash memory and replace -the firmware. This is the most promising method to upgrade (or -downgrade) a Wavedrum. - -The pins on the bottom row are all connected to ground, so the -following table only lists the signal names of the upper row of the -connector in order from left to right: - - -. | Signal | Full name ---+---------+------------------------ -1 | `~EMU` | Emulation status -2 | `GND` | Ground -3 | `TMS` | Test mode select -4 | `TCK` | Test clock -5 | `~TRST` | Test reset -6 | `TDI` | Test data input -7 | `TDO` | Test data output - - - -# CN12: two-wire serial interface - -CN12 exposes the DSP's two-wire interface, a serial interface -compatible with the proprietary I^2C interface. This allows us to -connect a number of external serial devices to the serial bus. As -firmware support is required to communicate with the devices on the -serial bus I don't see how this could be used without a custom -firmware. - -The following table lists the signals from top to bottom: - -. | Signal | Full name ---+------------+------------------------ -1 | `V_D` | Positive voltage -2 | `TWI_DATA` | Two-wire interface data -3 | `TWI_CLK` | Two-wire interface clock -4 | `GND` | Ground - - -# Bonus: boot mode - -What led me to tracing the routes of the connectors was my curiosity -about the boot mode. According to the DSP's datasheet, there are four -possible boot modes to select from by playing with the states of the -pins `BOOT_CFG1-0` (one of these boot modes is "no boot"). Tracing -these two pins from the DSP it becomes clear that the third boot mode -"EPROM/FLASH boot" is hardwired (`BOOT_CFG1-0 = 10`). The other two -usable boot modes are SPI master and slave boots. - -BOOT_CFG1-0 | Booting Mode --------------+-------------------- -00 | SPI Slave Boot -01 | SPI Master Boot -10 | EPROM/Flash Boot -11 | No boot - -<img class="full stretch" src="/images/posts/2013/wavedrum-bootcfg.jpg" alt="boot configuration traces" /> - -As can be seen on the photo, the Wavedrum engineers were kind enough -to leave solder pads connected to boot configuration pins on the -board, allowing us to rewire them as we see fit. To set `BOOT_CFG0` -the pads for `R72` have to be bridged; likewise, to clear `BOOT_CFG1` -only the two pads of `R59` have to be bridged. - - -# References - -- [ADSP-21371/ADSP-21375 datasheet](http://www.analog.com/static/imported-files/data_sheets/ADSP-21371_21375.pdf) -- [ADSP hardware reference](http://www.analog.com/static/imported-files/processor_manuals/ADSP-21367_hwr_rev2-1.pdf) |