Duovero Multiplexes

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This wiki entry concentrates on the Duovero Parlor board and the Multiplexes available from the 40 pin connector.

Duovero parlor conn small.png

The ground pin is nearest the console connector port and the power pins are nearest the centre of the board. This is as of writing but it is highly recommended that you check before connecting! Use a voltmeter to check the 3.3V, 5V and 1.8V pins to familiarise yourself with the layout.

There are also two connections on the Parlor board:

OMAP Pin GPIO # Purpose
AG24 GPIO121 user push button
AH24 GPIO122 user LED

You should start your journey here.

The primary reference for multiplexes and pin functions is the Texas Instruments OMAP4 technical reference manual. The short version of that 6000 page manual is the OMAP4430 datasheet which is easier to search. The primary source reference is in the Uboot code, specifically duovero_mux_data.h which uses the defines from ./arch/arm/include/asm/arch-omap4/mux_omap4.h.


Software Muxing

A helpful post from Phil Lutz describes how multiplexing can be explored without kernel recompilation. The default multiplex for the user LED may not be set to GPIO in Uboot. It certainly is not set to GPIO by the OMAP itself. You can look at the OMAP datasheet on page 48 you can see that the official name for GPIO 122 pin is "abe_dmic_din3" (Mode 0 names are accepted pin names).

This information can also be found by searching for "gpio_122" in the board pinmuxing configuration stored in sysfs: /sys/kernel/debug/omap_mux/board/core. Every pin which can be configured as gpio has a hint about that.

So now just check which is the current pinmuxing configuration for this pin by:

$ cat /sys/kernel/debug/omap_mux/abe_dmic_din3 
name: abe_dmic_din3.abe_dmic_din3 (0x4a100116/0x116 = 0x0100), b ah24, t NA
mode: OMAP_PIN_INPUT | OMAP_MUX_MODE0
signals: abe_dmic_din3 | slimbus2_data | abe_dmic_clk2 | gpio_122 | NA | dmtimer9_pwm_evt | NA | safe_mode

As the output suggests, the pin is configured in MODE0, this is 'abe_dmic_din3'. The other modes are listed in order as they appear in the OMAP data manual. gpio_122 is multiplex MODE 3. You can set it with:

 $ echo 3 > /sys/kernel/debug/omap_mux/abe_dmic_din3

Now you can turn on and off the LED using the usual gpio configuration in /sys/class/gpio/ (google it!). Note that "echo 3" does more than set Mode 3. The number is a selection of bits that set various states for the pin. A quick summary is:

Bit 0,1,2 Set the mode
Bit 3 0 = pull up/down disabled , 1 = enabled
Bit 4 0 = pull down, 1 = pull up
Bit 8 0 = Output only. 1 = input enable (bidirectional)

There are more but these are for sleep modes and wakeup. The manual has details. The defines in mux_omap4.h are useful for interpreting the duovero_mux_data.h file:

IEN 1 << 8 Input enable (bidirectional)
IDIS 0 << 8 Output only
PTU   3 << 3   Enable Pullup
PTD 1 << 3 Enable Pulldown
EN 1 << 3 PU/PD enable
DIS 0 << 3 PU/PD disable

Parlor pin mux table

To assist in figuring out which pins on the Parlor board can be assigned to which duties, here's a table of functions. Mode 7 is "safe_mode" where the pin is effectively disconnected from any functionality. It's set to high impedance (Z) and is left out of the table. The bolded functions are those set by the current U-Boot duovero_mux_data.h. This file sets other parameters (eg: output only, disable pullup/pulldown, etc) and you must refer to the U-Boot file to know what the full state is. A partial indication of the state (wake mode) is indicated in the table by arrows (bidirectional, output, pullup, pulldown).

Connector Description OMAP Pin Reset state Mode 0 Mode 1 Mode 2 Mode 3 Mode 4 Mode 5 Mode 6
User LEDa AH24 M7, Pulldown   abe_dmic_din3 slimbus2_data abe_dmic_clk2 gpio_122 - dmtimer9_pwm_evt -
Buttona AG24 M7, Pulldown abe_dmic_din2 slimbus2_clock abe_mcasp_axr gpio_121 - dmtimer11_pwm_evt -
04: MCSPI1_CS0 AE23 M7, Pulldown mcspi1_cs0 ⇔↓ - - gpio_137 - - -
06: MCSPI1_CS1 AF23 M7, Pulldown mcspi1_cs1 ⇔↓ uart1_rx - gpio_138 - - -
08: MCSPI1_CS2 AG23 M7, Pullup mcspi1_cs2 uart1_cts slimbus2_clock gpio_139 - - -
10: MCSPI1_CS3 AH23 M7, Pullup mcspi1_cs3 uart1_rts slimbus2_data gpio_140 - - -
03: MCSPI1_CLK AF22 M7, Pulldown mcspi1_clk - - gpio_134 - - -
05: MCSPI1_SIMO AG22 M7, Pulldown mcspi1_simo - - gpio_136 - - -
07: MCSPI1_SOMI AE22 M7, Pulldown mcspi1_somi - - gpio_135 - - -
09: HDQ_SIOb AA27 M7, Z hdq_sio i2c3_sccb i2c2_sccb gpio_127 - - -
12: I2C2_SCLc C26 M7, Pullup i2c2_scl ⇔↑ uart1_rx - gpio_128 - - -
14: I2C2_SDAc D26 M7, Pullup i2c2_sda ⇔↑ uart1_tx - gpio_129 - - -
11: SDMMC3_CMD AG10 M7, Pullup usbb2_ulpitll_dat6 usbb2_ulpiphy_dat6 sdmmc3_cmd gpio_167 ⇔↑ mcspi3_simo dispc2_data12 rfbi_data12
13: SDMMC3_CLK AE9 M7, Pullup usbb2_ulpitll_dat7 usbb2_ulpiphy_dat7 sdmmc3_clk gpio_168 ⇔↑ mcspi3_clk dispc2_data11 rfbi_data11
15: UART2_TX AA26 M7, Pullup uart2_tx sdmmc3_dat1 - gpio_126 - - -
17: UART2_RX AA25 M7, Pullup uart2_rx ⇔↑ sdmmc3_dat0 - gpio_125 - - -
19: BSP2_CLKX AD27 M7, Pulldown abe_mcbsp2_clkx mcspi2_clk abe_mcasp_ahclkx gpio_110 usbb2_mm_rxdm - -
20: BSP2_FSX AC28 M7, Pulldown abe_mcbsp2_fsx mcspi2_cs0 abe_mcasp_afsx gpio_113 usbb2_mm_txen - -
21: BSP2_DX AD25 M7, Pulldown abe_mcbsp2_dx mcspi2_simo abe_mcasp_amute gpio_112 usbb2_mm_rxrcv - -
22: BSP2_DR AD26 M7, Pulldown abe_mcbsp2_dr mcspi2_somi abe_mcasp_axr gpio_111 usbb2_mm_rxdp - -
23: BSP_CLKS AH26 M7, Pulldown abe_clks ⇔↓ - - gpio_118 - - -
25: MCSPI4_SOMI AF21 M7, Pullup mcspi4_somi sdmmc4_dat0 kpd_row6 gpio_153 - - -
27: MCSPI4_SIMO AF20 M7, Pullup mcspi4_simo sdmmc4_cmd kpd_col7 gpio_152 - - -
29: MCSPI4_CLK AE21 M7, Pulldown mcspi4_clk sdmmc4_clk kpd_col6 gpio_151 - - -
31: MCSPI4_CS0 AE20 M7, Pullup mcspi4_cs0 ⇔↓ sdmmc4_dat3 kpd_row7 gpio_154 - - -

Notes

a) Assigned as such in u-boot but reassigned in the kernel board startup code to Mode 3 Outputs

b) There is a 10K pull up to 1.8V, internal to the DuoVero COM, on the HDQ_SIO line. Do not enable a pull down on this line. This will result in a non-logic output level (approximately 1V). This is currently considered to be a bug and may be removed in future COM revisions.

c) There are pullups on I2C2 and I2C3 of approximately 1K. S/C current is over 2mA.

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