How can I set 10K of speed to I2c1 in u-boot

Bernie Chen

Other Parts Discussed in Thread: TCA6416A, TCA6416

Hello TI

This problem I suffered previously. That is i2c1 can't scan device of TCA6416A at 0x20, but it can scan other devices such 0x2D,0x50

U-Boot# i2c dev 1
Setting bus to 1

U-Boot# i2c probe
Valid chip addresses: 2D 50

So we want to down speed of i2c so that it maybe can scan 0x20. We have verified others of BSP can scan 0x20. I have referenced some document to know I must to write some value to I2C_PSC register,right? I print some value in u-boot/dirvers/i2c/omap24xx_i2c.c

void i2c_init(int speed, int slaveadd){

I2C_INTERNAL_SAMPLING_CLK is 12000000

speed is 100k

fsscll is 54

fssclh is 54

I2C_IP_CLK=48000000

psc=3

}

But I don't sure the next step, could anyone guide me ? Thank you.

over 10 years ago

0 Biser Gatchev-XID over 10 years ago

TI__Guru**** 393215 points

Hi,

Have you tried simply calling the function with the speed you require in Hz (10000)?

i2c_init(10000, ...)

0 Bernie Chen over 10 years ago in reply to Biser Gatchev-XID

Expert 2190 points

Yes , I have tried it. We make some revise in board.c

enable_i2c1_pin_mux();
i2c_set_bus_num(1);
i2c_init(10000/*CONFIG_SYS_I2C_SPEED*/, CONFIG_SYS_I2C_SLAVE);

But it is stuck at below when I boot from our board.

if ((speed != OMAP_I2C_STANDARD) &&
(speed != OMAP_I2C_FAST_MODE) &&
(speed != OMAP_I2C_HIGH_SPEED)) {
printf("Error : I2C unsupported speed %d\n", speed);
return;
}
psc = I2C_IP_CLK / I2C_INTERNAL_SAMPLING_CLK;
psc -= 1;
if (psc < I2C_PSC_MIN) {
printf("Error : I2C unsupported prescalar %d\n", psc);
return;
}

if (((fsscll < 0) || (fssclh < 0)) ||
((fsscll > 255) || (fssclh > 255))) {
puts("Error : I2C initializing clock\n");
return;
}

And I comment all of them . But I don't know psc、fsscll and fssclh should be what value in the condition of speed of 10K?

0 Biser Gatchev-XID over 10 years ago in reply to Bernie Chen

TI__Guru**** 393215 points

Yes, the function calculates these values according to the input frequency. the 10k you want to achieve is not a standard I2C clock rate, so it will not be accepted as a value. You will need to look in the I2C section in the AM335X TRM Rev. L, but I'm not sure that the AM335X I2C will work at this low speed.

0 Bernie Chen over 10 years ago in reply to Biser Gatchev-XID

Expert 2190 points

Hi Biser

I revised writew(/*psc*/89, &i2c_base->psc); in i2c_init(){}, and I observe the speed of i2c becoming slowly, but steel don't scan 0x20 (TCA6416A), where can we check? Thank you.

0 Biser Gatchev-XID over 10 years ago in reply to Bernie Chen

TI__Guru**** 393215 points

TCA6416A has a reset pin. Have you checked its state? It has to be high for proper operation.

0 Bernie Chen over 10 years ago in reply to Biser Gatchev-XID

Expert 2190 points

Yes, I let hardware engineer to measure signal,and the signal is high from u-boot to kernel.

0 Biser Gatchev-XID over 10 years ago in reply to Bernie Chen

TI__Guru**** 393215 points

It seems to me that this is either a defective component or problem with I2C waveforms. The TCA6416A should work with no problem up to 400kHz.

0 Bernie Chen over 10 years ago in reply to Biser Gatchev-XID

Expert 2190 points

Hi TI

I can detect i2c device now.

0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: UU -- -- -- -- -- -- -- -- -- -- -- -- 2d -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: UU -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- --

GPIOs 64-95, gpio:

GPIOs 96-127, gpio:
gpio-104 (wlan_en ) out lo
gpio-117 (bt_en
) out lo

GPIOs 192-207, i2c/2-0020, tca6416, can sleep:

What I concern is how do I control the P port of TCA6416A of datasheet in user level. Thank you.

0 Biser Gatchev-XID over 10 years ago in reply to Bernie Chen

TI__Guru**** 393215 points

See these: http://linux.die.net/man/8/i2cset and http://linux.die.net/man/8/i2cget

0 Bernie Chen over 10 years ago in reply to Biser Gatchev-XID

Expert 2190 points

Hi Biser

I know this i2c tools , maybe I can directly export the expand gpios to control low or high, thank you. I will try it tomorrow.

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How can I set 10K of speed to I2c1 in u-boot