TouchKey_TAC8418 , I2C read issue

Hello Hoo,

Thanks for the question.

1) To clear the buffer, the process depends on how you have the device set up. If you are using keyscan mode, you must first read the FIFO register A ( register 0x04) until you get 0x00 from it. Then you will need write a 0xFF to INT_STAT (0x02) to clear the interrupt status bits. If your FIFO is empty and your GPIO_INT_STAT registers are all 0x00, then the device will deassert (release) the INT pin and allow it to rise.

If you are NOT using keyscan mode, then you simply need to read the GPIO_INT_STAT registers, unless you activated GPI events in the FIFO, then you need to do what I outlined above plus reading the GPIO_INT_STAT registers before writing 0xFF to 0x02.

2) I can provide help with your device crashing issue, but I will need some more information. Could you explain what you mean by read TCA8418 faster? The device will operate on the I2C bus up to 400kHz. What are you steps that you take to make the device crash and I assume you mean the device NACKs when you address it? Also, do you have a schematic I could look at to better help you?

Hello Jonathan Valdez ,

My devices are using key scan mode now.

If the user press any key over 10 times in some function processing.

The is code processing flow.

1) Key A event

2) function A processing.

3) Key A,B,C,D... event over 10 times.

4) function A done.

5) Key read the FIFO register A until 10 times  or FIFO register = 0, delay 30ms per read. (For clear FIFO buffer)

6) function done.

7) The device is sometime crash.

Please give me any suggestion. Thank you.

Best Regards,

Hi Jonathan,

I thought Keypad Lock/Unlock can solve my issue.

I tried to set Configuration Register (Address 0×01) , K_LCK_IEN |= 0x04.

Then , I read Configuration Register , K_LCK_IEN(bit2) = 1.

Then , I hit key pad , KEY_EVENT_A != 0x00. The KEY_EVENT_A  didn't work.

//=========================

void I2C_KEYPad_LOCK()
{
Uint16 u16_Value = 0;
Uint16 u16_I2C_LEY_Buf1 = 0;
Uint16 rdData[2];
u16_I2C_LEY_Buf1 = I2C_KEY_Reader((Uint16)REG_CFG, (Uint16 *)&rdData);
u16_Value = (u16_I2C_LEY_Buf1 | 0x04);
I2C_KEY_Writer(I2C_KEY_SLAVEADDR , REG_CFG , u16_Value);
u16_I2C_LEY_Buf1 = I2C_KEY_Reader((Uint16)REG_CFG, (Uint16 *)&rdData);
}

//=========================

Could you please give me suggestion what's the cause?

How to prevent the generation of key event interrupts and recorded key events?

Per 9.2.1.1 Keypad Lock/Unlock description as below.

This user can lock the keypad through the lock/unlock feature in this device. Once the keypad is locked, it can

prevent the generation of key event interrupts and recorded key events. The unlock keys can be programmed

with any value of the keys in the keypad matrix or any GPI values that are part of the key event table. When the

keypad lock interrupt mask timer is enabled, the user will need to press two specific keys before an keylock

interrupt is generated or keypad events are recorded. After the keypad is locked, a key event interrupt is

generated any time a user presses a key. This first interrupt also triggers the processor to turn on the LCD and

display the unlock message. The processor will then read the lock status register to see if the keypad is

unlocked. The next interrupt (keylock interrupt) will not be generated unless both unlock keys sequences are

correct. If correct Unlock keys are not pressed before the mask timer expires, the state machine will start over

again.

Best Regards,

Hello Hoo,

Excuse my delay, I am out of the office on business travel currently.

I think you have a mis understanding of the descriptions.

When you wrote K_LCK_IEN, you merely enabled key lock interrupt, which allows interrupts to be sent to alert the processor that a keypad has been unlocked or locked. It does not force a keypad lock.

I currently do not have access to the materials required to walk you through all the steps to setup the keypad (since i'm out of office). I will have to get back to you on this.

In short, what I do remember off the top of my head is that you must enable the keypad lock. Once th ekeypad is locked, you set the two unlock registers for the key presses you want to unlock th ekeypad.

There is a register that controls the timing of these interrupts, and if you wish for the TCA8418 to send you no interrupts at all, you must set these to 0. This feature of sending 1 interrupt is aimed at phones, where the user may have a locked keypad, but they still want a button press to turn on the screen.

Hello Hoo,

I am out of the office until Friday. We do not have any sample code of this function, but I will help you with the procedure needed to execute this.

Perhaps you did not include it in your code, but I do not see a KeyValue variable defined anywhere, and it would seem that the key_lock() function never gets called as a result?

In your key_init function, you should just set the u16_value to = 0x03 instead of ORing it with 0x07. We want the interrupt mask to be 0, you set it to 1 second.

Hi Jonathan ,

If u16_value = 0x03 at key_init , it should be Lock1 only.

TCA8418 datasheet is discription , KP_LCK_TIMER / KL[2:0] are for the Lock1 to Lock2 timer.

Should I set Lock1 only?

What is  interrupt mask to be 0,you set it to 1 second? Is it mean REG_KEY_LCK_EC / bit6 ?

Please kindly guide me the init and process flow for TCA8418 Lock and un-Lock function.

Below is key define.

#define REG_CFG 0x01

#define REG_INT_STAT 0x02
#define REG_KEY_LCK_EC 0x03
#define REG_KEY_EVENT_A 0x04
#define REG_KEY_EVENT_B 0x05
#define REG_KP_LCK_TIMER 0x0E
#define REG_UNLOCK1 0x0F
#define REG_UNLOCK2 0x10

Best Regards,

Hi Jonathan ,

I tried these setting as below.
My device is loop in DDC_i2cTransfer(); // Please refer DDC_i2cTransfer code
I cannot set un-lock command to I2C bus.

while (cnt < bufLen) // If set key lock , it will loop in cnt < bufLen forever...
{
...
}



#define Left 0x80
main()
{
Uint16 KeyValue = 0;

I2C_init();


while(1)
{
KeyValue = GetKeyValue();
if(KeyValue == Left)
{
Key_lock(); // REG_KEY_LCK_EC |= 0x40
}

}

}





Best Regards,

Hello Hoo,

Now that I am in the office,I am able to test this myself to verify operation.

As such, I just double checked to verify the following:

To lock: You need to write a 1 to bit 6 (0x40) in register 0x03 (KEY_LCK_EC). Doing this will immediately lock the keyboard.

To unlock: You may either write a 0 to bit 6 in register 0x03, or you may use the keypress combination.

 To program the unlock keys, you must program registers 0x0F and 0x10 (Unlock 1 and 2) to tell the device which key combination can unlock it. See below table for key values from datasheet on page 29:

Lets say you want the key connect to C0 and R0 to be the first button press required (key 1), you would write 0x01 to register 0x0F.

Then lets say you want the 2nd key press to be key 23 (R2 and C2), you would write 0x17 to register 0x10.

Once these two registers are programmed and you have locked the keypad (write 0x40 to register 0x03), you won't get any interrupts until you press key 1 then 23. Once you press these two, you will get an interrupt (assuming you have K_LCK_IEN bit set in 0x01 register) letting you know an unlock has occured (can be checked by looking to see if Bits 5 and 4 in register 0x03 are 0 or 1 to signify whether its locked). Then any further key presses will send interrupts as expected until you lock the keyboard again.