Search found 16 matches

by aschweiz
Thu Jan 19, 2017 10:40 am
Forum: Report Bugs
Topic: Potential timing issue in wifi stack or mbedtls?
Replies: 0
Views: 27

Potential timing issue in wifi stack or mbedtls?

Hi, I noticed sporadic issues in a project where I use the mbedTLS functions to connect to a web server with HTTPS, such as blocking mbedtls_ssl_handshake or errors in subsequent read/write operations (e.g. -0x7880). (Well, not really sporadic - it failed about 50% of the time ;-) By trial-and-error...
by aschweiz
Sat Jan 07, 2017 1:19 pm
Forum: Report Bugs
Topic: Unexpectedly low floating-point performance in C
Replies: 10
Views: 560

Re: Unexpectedly low floating-point performance in C

Hi Greenja, good point :) Indeed, the code on the STM32F767 was run without RTOS. However I need to disappoint you - I've repeated the test with the code running in a FreeRTOS task on the STM32F767 and the numbers are still more or less the same. Attached is the assembly output of the compiler. The ...
by aschweiz
Sat Jan 07, 2017 12:59 pm
Forum: Report Bugs
Topic: Unexpectedly low floating-point performance in C
Replies: 10
Views: 560

Re: Unexpectedly low floating-point performance in C

Hi Angus,

attached is the test code. Let me know if you need more information or other files.

cheers
Andreas
by aschweiz
Fri Jan 06, 2017 9:37 am
Forum: ESP32 SDK
Topic: Bluetooth LE API questions: esp_ble_gatts_app_register
Replies: 2
Views: 84

Re: Bluetooth LE API questions: esp_ble_gatts_app_register

I also wonder about these points. About your last question, I noticed a few things: The "GATT server" example uses the same UUID for the service and the call to esp_ble_gatts_app_register. However, there's a restriction on the UUID you can send to the esp_ble_gatts_app_register. It can onl...
by aschweiz
Thu Jan 05, 2017 10:32 am
Forum: Report Bugs
Topic: Flags ignored in BLE advertising
Replies: 2
Views: 141

Re: Flags ignored in BLE advertising

I think I've found the issue: It seems that the flags are lost in the BLE stack, in file "btc_gap_ble.c", function "btc_to_bta_adv_data". The input object "p_adv_data" still contains them, but they're not copied to the output object "bta_adv_data". By changing...
by aschweiz
Wed Jan 04, 2017 3:34 pm
Forum: Report Bugs
Topic: Unable to add more than 1 characteristic to a service
Replies: 1
Views: 117

(Solved) Re: Unable to add more than 1 characteristic to a service

Fyi, it's working fine after I've increased the number of handles in esp_ble_gatts_create_service :-)
by aschweiz
Fri Dec 23, 2016 4:43 pm
Forum: Report Bugs
Topic: Unexpectedly low floating-point performance in C
Replies: 10
Views: 560

Re: Unexpectedly low floating-point performance in C

Hi Neil, that was also my first guess, but it turns out that it just takes 200 nanoseconds to toggle the output high and low again. Meanwhile, I also tried the idea with the loop and the performance is much better. Doing an "f1 += f2" 100 times takes only 64 microseconds, 640 nanoseconds p...
by aschweiz
Fri Dec 23, 2016 1:51 pm
Forum: Report Bugs
Topic: Unexpectedly low floating-point performance in C
Replies: 10
Views: 560

Re: Unexpectedly low floating-point performance in C

additional info, assembly output of the compiler generated with -save-temps, plus some comments from the Xtensa instruction set architecture reference manual: call8 vTaskSuspendAll .LVL110: .loc 1 272 0 movi.n a11, 1 movi.n a10, 0x12 call8 gpio_set_level <------ t=0 .LVL111: .loc 1 273 0 l32r a3, .L...
by aschweiz
Fri Dec 23, 2016 1:48 pm
Forum: Report Bugs
Topic: Unexpectedly low floating-point performance in C
Replies: 10
Views: 560

Unexpectedly low floating-point performance in C

Hi, according to the datasheet, the ESP32 seems to contain a hardware FPU, but in my tests, I get very bad FPU performance. For example, the following addition of two "float" variables and assignment to a third "float" variable (all 3 declared as volatile so that they don't get o...
by aschweiz
Wed Dec 21, 2016 3:29 pm
Forum: Report Bugs
Topic: Unable to add more than 1 characteristic to a service
Replies: 1
Views: 117

Unable to add more than 1 characteristic to a service

I'm adding two characteristics to a service in the ESP_GATTS_CREATE_EVT event: gl_test.char_uuid[0].len = ESP_UUID_LEN_16; gl_test.char_uuid[0].uuid.uuid16 = ...; esp_ble_gatts_add_char(gl_test.service_handle, &gl_test.char_uuid[0], ESP_GATT_PERM_READ, ESP_GATT_CHAR_PROP_BIT_READ); gl_test.char_...