Part Number: AM62A7-Q1
Other Parts Discussed in Thread: SYSCONFIG
Hello:
below is the hardware design for am62a product. Right now I need to PORT "B12" and "C11" to monitor two switch MODE_SW1 and MODE_SW2. And right now I can not see in sysconfig the GPIO0 and GPIO1 have this pin. can you check if i can use this pin for GPIO input in my linux sdk or not . thanks very much
Hello Meng Ke,
Thank you for the query.
Please refer below.
Regards,
Sreenivasa
Hello Meng Ke,
I received some input from the device expert regarding the connection of the push button to SOC IO and need for external ESD protection
Option 1:
You may want to move the switch connecting to pin B12 to one of the other pins that has the hardware debounce function on its GPIO. This could potentially prevent from having to do a software debounce of the switch. The GPIO associated with pin C11 has the hardware debounce function.
The SOC GPIOs supporting hardware debounce is included in the below section
Data sheet section reference
5.3 Signal Descriptions
5.3.10 GPIO
5.3.10.1 MAIN Domain
(1) This GPIO input signal has a debounce function. For more information on I/O Debounce configuration, see the TRM Device
Configuration chapter.
TRM section reference
6.1 Control Module
6.1.2 I/O Debounce Control Registers
Some device pads have debounce logic. The following MCU_CTRL_MMR0 registers are used to configure the
debounce period:
• MCU_CTRL_MMR_DBOUNCE_CFG1
• MCU_CTRL_MMR_DBOUNCE_CFG2
• MCU_CTRL_MMR_DBOUNCE_CFG3
• MCU_CTRL_MMR_DBOUNCE_CFG4
• MCU_CTRL_MMR_DBOUNCE_CFG5
• MCU_CTRL_MMR_DBOUNCE_CFG6
Option 2
Adding external debounce cap across the switch
I do not see any cap added to the switch connected externally for debounce. Trying to understand internal SOC debounce logic suffice. I suspect the debounce time can be configured.
A capacitor should not be needed when using the hardware debounce function. There is some programmability, refer to the TRM to get the details.
The recommendation is use a buffer between the switch and our input when using a capacitor because we do not allow a rise/fall longer than 1000ns and switch bounce is very likely to last longer than 1000ns. So using a capacitor alone is not a valid solution.
The buffer used on a capacitor debounced switch should have a Schmitt trigger input that provides hysteresis to the input switching threshold.
Refer SK schematics for implementation.
Additional inputs regarding external ESD protection.
All processor signals which come in close proximity of a human touch should have ESD protection. It helps to use a shielded switch, but I would still recommend ESD protection on any signal connected to a switch that can be operated by a human.
Regards,
Sreenivasa
