Duovero Multiplexes

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

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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).

Underneath the gpio entries are the GPIO register and bit offset. These numbers are useful for device tree purposes.

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 GPIO4[26]	-	dmtimer9_pwm_evt	-
Buttona	AG24	M7, Pulldown	abe_dmic_din2 ⇔	slimbus2_clock	abe_mcasp_axr	gpio_121 GPIO4[25]	-	dmtimer11_pwm_evt	-
04: MCSPI1_CS0	AE23	M7, Pulldown	mcspi1_cs0 ⇔↓	-	-	gpio_137 GPIO5[9]	-	-	-
06: MCSPI1_CS1	AF23	M7, Pulldown	mcspi1_cs1 ⇔↓	uart1_rx	-	gpio_138 GPIO5[10]	-	-	-
08: MCSPI1_CS2	AG23	M7, Pullup	mcspi1_cs2	uart1_cts	slimbus2_clock	gpio_139 GPIO5[11]	-	-	-
10: MCSPI1_CS3	AH23	M7, Pullup	mcspi1_cs3	uart1_rts	slimbus2_data	gpio_140 GPIO5[12]	-	-	-
03: MCSPI1_CLK	AF22	M7, Pulldown	mcspi1_clk ⇔	-	-	gpio_134 GPIO5[6]	-	-	-
05: MCSPI1_SIMO	AG22	M7, Pulldown	mcspi1_simo ⇔	-	-	gpio_136 GPIO5[8]	-	-	-
07: MCSPI1_SOMI	AE22	M7, Pulldown	mcspi1_somi ⇔	-	-	gpio_135 GPIO5[7]	-	-	-
09: HDQ_SIOb	AA27	M7, Z	hdq_sio ⇒	i2c3_sccb	i2c2_sccb	gpio_127 GPIO4[31]	-	-	-
12: I2C2_SCLc	C26	M7, Pullup	i2c2_scl ⇔↑	uart1_rx	-	gpio_128 GPIO5[0]	-	-	-
14: I2C2_SDAc	D26	M7, Pullup	i2c2_sda ⇔↑	uart1_tx	-	gpio_129 GPIO5[1]	-	-	-
11: SDMMC3_CMD	AG10	M7, Pullup	usbb2_ulpitll_dat6	usbb2_ulpiphy_dat6	sdmmc3_cmd	gpio_167 ⇔↑ GPIO6[7]	mcspi3_simo	dispc2_data12	rfbi_data12
13: SDMMC3_CLK	AE9	M7, Pullup	usbb2_ulpitll_dat7	usbb2_ulpiphy_dat7	sdmmc3_clk	gpio_168 ⇔↑ GPIO6[8]	mcspi3_clk	dispc2_data11	rfbi_data11
15: UART2_TX	AA26	M7, Pullup	uart2_tx ⇒	sdmmc3_dat1	-	gpio_126 GPIO4[30]	-	-	-
17: UART2_RX	AA25	M7, Pullup	uart2_rx ⇔↑	sdmmc3_dat0	-	gpio_125 GPIO4[29]	-	-	-
19: BSP2_CLKX	AD27	M7, Pulldown	abe_mcbsp2_clkx ⇔	mcspi2_clk	abe_mcasp_ahclkx	gpio_110 GPIO4[14]	usbb2_mm_rxdm	-	-
20: BSP2_FSX	AC28	M7, Pulldown	abe_mcbsp2_fsx ⇔	mcspi2_cs0	abe_mcasp_afsx	gpio_113 GPIO4[17]	usbb2_mm_txen	-	-
21: BSP2_DX	AD25	M7, Pulldown	abe_mcbsp2_dx ⇒	mcspi2_simo	abe_mcasp_amute	gpio_112 GPIO4[16]	usbb2_mm_rxrcv	-	-
22: BSP2_DR	AD26	M7, Pulldown	abe_mcbsp2_dr ⇔	mcspi2_somi	abe_mcasp_axr	gpio_111 GPIO4[15]	usbb2_mm_rxdp	-	-
23: BSP_CLKS	AH26	M7, Pulldown	abe_clks ⇔↓	-	-	gpio_118 GPIO4[22]	-	-	-
25: MCSPI4_SOMI	AF21	M7, Pullup	mcspi4_somi ⇔	sdmmc4_dat0	kpd_row6	gpio_153 GPIO5[25]	-	-	-
27: MCSPI4_SIMO	AF20	M7, Pullup	mcspi4_simo ⇔	sdmmc4_cmd	kpd_col7	gpio_152 GPIO5[24]	-	-	-
29: MCSPI4_CLK	AE21	M7, Pulldown	mcspi4_clk ⇔	sdmmc4_clk	kpd_col6	gpio_151 GPIO5[23]	-	-	-
31: MCSPI4_CS0	AE20	M7, Pullup	mcspi4_cs0 ⇔↓	sdmmc4_dat3	kpd_row7	gpio_154 GPIO5[26]	-	-	-

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.