Search found 12 matches

by chopin1998
Wed May 10, 2017 9:21 am
Forum: General Discussion
Topic: can I use esp32 as a bluetooth TAG, and limit esp32 tx range in 0.5m?
Replies: 0
Views: 1380

can I use esp32 as a bluetooth TAG, and limit esp32 tx range in 0.5m?

这个可以被实现吗?

Could it be implemented?
by chopin1998
Thu Mar 23, 2017 3:58 am
Forum: General Discussion
Topic: only three slave can be attached in SPI ?
Replies: 8
Views: 6632

Re: only three slave can be attached in SPI ?

Ooops.... I can set spics_io_num = -1, but when I call spi_bus_add_device > 3 times, driver still said E (199) spi_master: spi_bus_add_device(326): no free cs pins for host .... If you wan to use more than 3 devices, you have to modify spi_bus_add_device() function, something like this: #define NO_...
by chopin1998
Wed Mar 22, 2017 6:53 am
Forum: General Discussion
Topic: only three slave can be attached in SPI ?
Replies: 8
Views: 6632

Re: only three slave can be attached in SPI ?

maybe i call spi_bus_add_device once, with a dummy CS pin number, and select CS via GPIO manually? why the API has this limit? You can set the divice configuration not to use CS ( spics_io_num = -1 ) in spi_device_interface_config_t structure int spics_io_num; ///< CS GPIO pin for this device, or -...
by chopin1998
Tue Mar 21, 2017 9:01 am
Forum: General Discussion
Topic: only three slave can be attached in SPI ?
Replies: 8
Views: 6632

Re: only three slave can be attached in SPI ?

yeah, i did this and use .pre_cb and .post_cb to tgl CS pin

thank you!
by chopin1998
Tue Mar 21, 2017 3:08 am
Forum: General Discussion
Topic: only three slave can be attached in SPI ?
Replies: 8
Views: 6632

Re: only three slave can be attached in SPI ?

maybe i call spi_bus_add_device once, with a dummy CS pin number, and select CS via GPIO manually?

why the API has this limit?
by chopin1998
Tue Mar 21, 2017 3:01 am
Forum: General Discussion
Topic: only three slave can be attached in SPI ?
Replies: 8
Views: 6632

only three slave can be attached in SPI ?

i have layouted a PCB, esp32 connect 5 spi slave, share same CLK/ MISO/ MOSI and 5 independent nCS to every device. but when I use spi_bus_add_device() 5 times, it said: E (199) spi_master: spi_bus_add_device(326): no free cs pins for host E (199) spi_master: spi_bus_add_device(326): no free cs pins...
by chopin1998
Fri Jan 13, 2017 7:30 am
Forum: Hardware
Topic: External Interrupt Latency
Replies: 14
Views: 13515

Re: External Interrupt Latency

I have done a measurement and delay from external trigger to application-provided ISR handler is around 2us (at 240MHz clock), which is around 500 cycles. yes, real interrupt delay is about 1.7~1.8uS, it seems too long for a 240Mhz processor, I measure the delay on a 32Mhz 8bit mcu, delay is ~700nS...
by chopin1998
Wed Jan 11, 2017 10:33 am
Forum: General Discussion
Topic: how to use esp32 input capture and motor pwm function?
Replies: 15
Views: 16679

Re: how to use esp32 input capture and motor pwm function?

You might get some mileage from a study of the unusually named "Remote" peripheral functions in the ESP32. This is also called "RMT". The name stems from the apparent mapping to an "infrared remote control" interface where we can supply a signal pattern to RMT and RMT will then own the generation o...
by chopin1998
Tue Jan 10, 2017 7:25 am
Forum: General Discussion
Topic: how to use esp32 input capture and motor pwm function?
Replies: 15
Views: 16679

Re: how to use esp32 input capture and motor pwm function?

You might get some mileage from a study of the unusually named "Remote" peripheral functions in the ESP32. This is also called "RMT". The name stems from the apparent mapping to an "infrared remote control" interface where we can supply a signal pattern to RMT and RMT will then own the generation o...

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