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joule: align SPI bus numbering with reality

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Also update docs to make the numbering and pins used crystal clear.

Closes #758.

Signed-off-by: Alex Tereschenko <alext.mkrs@gmail.com>
This commit is contained in:
Alex Tereschenko
2017-06-15 20:49:18 +02:00
parent 000746c20d
commit 32196d10e9
2 changed files with 22 additions and 22 deletions
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32
docs/joule.md
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@@ -14,26 +14,22 @@ Interface notes
**SPI**
Two SPI buses are available, with one chipselect each. Pins listed are MRAA
numbered pins. Other chip selects are available if enabled in BIOS/EEPROM but
cannot be enabled as BIOS options. You will need the spidev kernel module
loaded, Ostro-XT and ref-os-iot does this by default.
Two SPI buses are available, one with three and another one with two chipselects.
In MRAA terms an SPI "bus" (denoted by a number) is a combination
of an actual bus + specific chipselect on this bus. In view of that + taking
into account that SPI1CS1 is not available on the board, in MRAA the above
translates into five available bus numbers - from 0 to 4, covering SPI0CS0 to SPI1CS2.
Bus 0 (32765)
MOSI = 4
MISO = 2
CS = 6
CLK = 10
Pins listed are MRAA numbered pins. You will need the `spidev` kernel module loaded
with appropriate board configuration for binding, Ref-OS-IoT does not enable this by default.
Bus 1 (32766)
MOSI = 67
MISO = 69
CS0 = 59
CS1 = 61
CLK = 65
(remove 40 from numbers to get pin header number for pins on low speed header
2)
MRAA bus # | Ref-OS-IoT bus # | Joule docs bus # | MOSI | MISO | CLK | CS
-----------|------------------|------------------|------|------|-----|----
0 | 32766 | SPI0 | 67 (J13-27)| 69 (J13-29) | 65 (J13-25) | 59 (J13-19)
1 | 32766 | SPI0 | 67 (J13-27)| 69 (J13-29) | 65 (J13-25) | 61 (J13-21)
2 | 32766 | SPI0 | 67 (J13-27)| 69 (J13-29) | 65 (J13-25) | 63 (J13-23)
3 | 32765 | SPI1 | 4 (J12-4)| 2 (J12-2) | 10 (J12-10) | 6 (J12-6)
4 | 32765 | SPI1 | 4 (J12-4)| 2 (J12-2) | 10 (J12-10) | 8 (J12-8)
**UART** Some pins are labelled as UARTs but are not configured in BIOS as UART
so only available UART is on the FTDI header. Disable the getty on ttyS2 and