Let me base this on the board I chose in the previous article. It\u2019s the so-called BlackPill with STM32F401<\/a> onboard. You can buy such a board<\/a> (or a slightly more powerful one<\/a>) from me.<\/p>\n\n\n <\/p>\n\n\n\n The software I\u2019ll use is:<\/p>\n\n\n\n I\u2019ll also base this on the project I created for STM32F4<\/a>.<\/p>\n\n\n\n Translating this into Polish, it would be \u201cStempel Czasu\u201d (like from Harry Potter, darn it). This function works such that during a \u201cbreak-in\u201d, i.e., when an edge is detected on a dedicated pin, the date and time are latched. This is done \u201csilently\u201d, so the intruder won\u2019t realize what happened.<\/p>\n\n\n\n We can immediately send such registered tampering remotely to headquarters or store it in logs in non-volatile memory.<\/p>\n\n\n\n First, you need to enable this function in Cube by checking it.<\/p>\n\n\n A configured GPIO pin will appear on PC13. It will serve as the stamp source.<\/p>\n\n\n <\/p>\n\n\n\n An additional section will appear in the RTC configuration.<\/p>\n\n\n <\/p>\n\n\n\n Select which edge you\u2019re interested in here. I chose the falling edge. On pin PC13 I additionally added a 10 k\u03a9 pull-up resistor to supply. You can\u2019t set an internal Pull Up for a special pin.<\/p>\n\n\n\n The Event Time Stamp generates an interrupt. Of course, in HAL we\u2019ll find its handler that we can implement. In it, I read the date and time of the occurrence and set my own flag, which I\u2019ll use in the main loop.<\/p>\n\n\n\n I use this flag in the main loop to print the stamp date and time. The rest of the time, every second I send data from the RTC to the serial port.<\/p>\n\n\n\n And here is the effect in action.<\/p>\n\n\n <\/p>\n\n\n\n After the falling edge appears, an interrupt occurs and it\u2019s printed to serial. Simple \ud83d\ude42 You can find the full example code here<\/a>.<\/p>\n\n\n\n I already mentioned this function in the context of the F1 articles because it\u2019s present there as well. Its operation consists in clearing the backup registers after detecting an edge on a dedicated pin. It\u2019s a kind of anti-burglar. When someone tries to break into a device and opens the enclosure, we can automatically erase sensitive data from battery-backed registers.<\/p>\n\n\n\n To set Tamper, it\u2019s enough to check the appropriate box in Cube.<\/p>\n\n\n Here too, a configured pin will appear on the microcontroller diagram.<\/p>\n\n\n And of course, new options appeared in the RTC configuration<\/p>\n\n\n These are mainly pin behavior options.<\/p>\n\n\n\n The event that triggers Tamper not only erases the contents of the backup registers, but it can also trigger an interrupt. In the example I use it to set Tamper again.<\/p>\n\n\n\n In the main loop I set the registers and wait for the Tamper event. I connected a button and an external Pull Up to the board so that it works correctly (not that precharged Pull Up, because there\u2019s an LED). After the Tamper interrupt occurs, I only set a flag, and then after checking it I print the register contents, fill them again, and set Tamper once more.<\/p>\n\n\n\n Here is the result:<\/p>\n\n\n <\/p>\n\n\n\n The registers are nicely cleared \ud83d\ude42 You can find the full example code here<\/a>.<\/p>\n\n\n\n In the Tamper setup there was something like Time Stamp On Tamper Detection. <\/em>During normal Tamper operation, we clear the registers and that\u2019s it.<\/p>\n\n\n\n Sometimes, however, there may be a need where you\u2019d like to know a bit more about this break-in. For example, when it happened. That\u2019s exactly what combining these two functions enables \u2013 clearing and recording the date and time of the event.<\/p>\n\n\n\n It\u2019s enough to set this one bit in the Tamper configuration to combine these two functions.<\/p>\n\n\n\n Then, in the Tamper handler, it\u2019s enough to read the special Time Stamp registers, which store the information about when it happened and\u2026 that\u2019s it \ud83d\ude42 Two birds with one stone. Simple, right?<\/p>\n\n\n <\/p>\n\n\n\n You can find the full example code here<\/a>.<\/p>\n\n\n\n As you can see, using the additional features of the built-in RTC is not complicated. Remember that these functions, like the entire clock module, work during battery power. This means that a \u201cbreak-in\u201d during battery operation is recorded in special registers intended for these functions. This is a very valuable property because we don\u2019t always want the MCU to be running at full speed.<\/p>\n\n\n\n In the next post I\u2019ll cover functions related to waking up the microcontroller and\u2026 a human \ud83d\ude42<\/p>\n\n\n\n You\u2019ll find the full project along with the library as usual on my GitHub: LINK<\/a><\/p>\n\n\n\n If you noticed an error, disagree with something, would like to add something important, or simply feel like you\u2019d like to discuss this topic, write a comment. Remember that the discussion should be polite and follow the rules of the Polish language.<\/span><\/p>\n\n\n![\"stm32f411\"](\"http:\/\/msalamon.pl\/wp-content\/uploads\/2019\/12\/BlackPill-baner.jpg\")
<\/a><\/figure>\n<\/div>\n\n\n\n
Time Stamp in STM32F4<\/h2>\n\n\n\n
![\"\"](\"http:\/\/msalamon.pl\/wp-content\/uploads\/2020\/03\/rtcf4_timestamp_cube.png\")
<\/figure>\n<\/div>\n\n\n![\"\"](\"http:\/\/msalamon.pl\/wp-content\/uploads\/2020\/03\/rtcf4_tamper_cube2.png\")
<\/figure>\n<\/div>\n\n\n![\"\"](\"http:\/\/msalamon.pl\/wp-content\/uploads\/2020\/03\/rtcf4_timestamp_cube2.png\")
<\/figure>\n<\/div>\n\n\nvoid HAL_RTCEx_TimeStampEventCallback(RTC_HandleTypeDef *hrtc)\n{\n HAL_RTCEx_GetTimeStamp(hrtc, &RtcTimeStamp, &RtcDateStamp, RTC_FORMAT_BIN);\n MillisecondsStamp = ((RtcTime.SecondFraction-RtcTimeStamp.SubSeconds)\/((float)RtcTime.SecondFraction+1) * 100);\n\tTimeStampFlag = 1;\n}<\/pre>\n\n\n\n \/* USER CODE BEGIN WHILE *\/\n while (1)\n {\n\t HAL_RTC_GetTime(&hrtc, &RtcTime, RTC_FORMAT_BIN);\n\t Milliseconds = ((RtcTime.SecondFraction-RtcTime.SubSeconds)\/((float)RtcTime.SecondFraction+1) * 100);\n\t HAL_RTC_GetDate(&hrtc, &RtcDate, RTC_FORMAT_BIN);\n\n\t if(RtcTime.Seconds != CompareSeconds)\n\t {\n\t\t MessageLen = sprintf((char*)Message, \"Date: %02d.%02d.20%02d Time: %02d:%02d:%02d:%02d\\n\\r\", RtcDate.Date, RtcDate.Month, RtcDate.Year, RtcTime.Hours, RtcTime.Minutes, RtcTime.Seconds, Milliseconds);\n\t\t HAL_UART_Transmit(&huart2, Message, MessageLen, 100);\n\t\t CompareSeconds = RtcTime.Seconds;\n\t }\n\n\t if(TimeStampFlag == 1)\n\t {\n\t\t MessageLen = sprintf((char*)Message, \"TimeStamp! Date: %02d.%02d.20%02d Time: %02d:%02d:%02d:%02d\\n\\r\", RtcDateStamp.Date, RtcDateStamp.Month,\n\t\t\t\t RtcDateStamp.Year, RtcTimeStamp.Hours, RtcTimeStamp.Minutes, RtcTimeStamp.Seconds, MillisecondsStamp);\n\t\t HAL_UART_Transmit(&huart2, Message, MessageLen, 100);\n\n\t\t TimeStampFlag = 0;\n\t }\n\n\t if(GPIO_PIN_RESET == HAL_GPIO_ReadPin(TEST_GPIO_Port, TEST_Pin))\n\t {\n\t\t while(GPIO_PIN_RESET == HAL_GPIO_ReadPin(TEST_GPIO_Port, TEST_Pin))\n\t\t {}\n\t\t SetRTC();\n\t }\n \/* USER CODE END WHILE *\/\n\n \/* USER CODE BEGIN 3 *\/\n }<\/pre>\n\n\n\n![\"\"](\"http:\/\/msalamon.pl\/wp-content\/uploads\/2020\/03\/rtcf4_timestamp.png\")
<\/figure>\n<\/div>\n\n\nTamper in STM32F4<\/h2>\n\n\n\n
![\"\"](\"http:\/\/msalamon.pl\/wp-content\/uploads\/2020\/03\/rtcf4_tamper_cube.png\")
<\/figure>\n<\/div>\n\n\n<\/figure>\n<\/div>\n\n\n![\"\"](\"http:\/\/msalamon.pl\/wp-content\/uploads\/2020\/03\/rtcf4_tamper_cube3.png\")
<\/figure>\n<\/div>\n\n\n\n
while (1)\n {\n\t HAL_RTC_GetTime(&hrtc, &RtcTime, RTC_FORMAT_BIN);\n\t Milliseconds = ((RtcTime.SecondFraction-RtcTime.SubSeconds)\/((float)RtcTime.SecondFraction+1) * 100);\n\t HAL_RTC_GetDate(&hrtc, &RtcDate, RTC_FORMAT_BIN);\n\n\t if(RtcTime.Seconds != CompareSeconds)\n\t {\n\t\t MessageLen = sprintf((char*)Message, \"Date: %02d.%02d.20%02d Time: %02d:%02d:%02d:%02d\\n\\r\", RtcDate.Date, RtcDate.Month, RtcDate.Year, RtcTime.Hours, RtcTime.Minutes, RtcTime.Seconds, Milliseconds);\n\t\t HAL_UART_Transmit(&huart2, Message, MessageLen, 100);\n\t\t CompareSeconds = RtcTime.Seconds;\n\t }\n\n\t if(TamperFlag == 1)\n\t {\n\n\t\t HAL_RTCEx_GetTimeStamp(&hrtc, &RtcTimeTimeStamp, &RtcDateTimeStamp, RTC_FORMAT_BIN);\n\t\t Milliseconds = ((RtcTime.SecondFraction-RtcTimeTimeStamp.SubSeconds)\/((float)RtcTime.SecondFraction+1) * 100);\n\n\t\t MessageLen = sprintf((char*)Message, \"Tamper detected at Time Stamp %02d.%02d.20%02d Time: %02d:%02d:%02d:%02d!\\n\\r\",RtcDateTimeStamp.Date, RtcDateTimeStamp.Month, RtcDateTimeStamp.Year,\n\t\t\t\t RtcTimeTimeStamp.Hours, RtcTimeTimeStamp.Minutes, RtcTimeTimeStamp.Seconds, Milliseconds);\n\t\t HAL_UART_Transmit(&huart2, Message, MessageLen, 100);\n\n\t\t MessageLen = sprintf((char*)Message, \"Backup Registers cleared:\\n\\r\");\n\t\t HAL_UART_Transmit(&huart2, Message, MessageLen, 100);\n\n\t\t for(int i = 0; i < BACKUP_COUNT; i++)\n\t\t {\n\t\t\t uint32_t tmp = HAL_RTCEx_BKUPRead(&hrtc, aBKPDataReg[i]);\n\t\t\t MessageLen = sprintf((char*)Message, \"%X, \", tmp);\n\t\t\t HAL_UART_Transmit(&huart2, Message, MessageLen, 100);\n\t\t }\n\n\t\t MessageLen = sprintf((char*)Message, \"\\n\\r\");\n\t\t HAL_UART_Transmit(&huart2, Message, MessageLen, 100);\n\n\t\t MessageLen = sprintf((char*)Message, \"Write example data to regs:\\n\\r\");\n\t\t HAL_UART_Transmit(&huart2, Message, MessageLen, 100);\n\n\t\t for(int i = 0; i < BACKUP_COUNT; i++)\n\t\t {\n\t\t\t HAL_RTCEx_BKUPWrite(&hrtc, aBKPDataReg[i], (i * 32));\n\t\t\t uint32_t tmp = HAL_RTCEx_BKUPRead(&hrtc, aBKPDataReg[i]);\n\t\t\t MessageLen = sprintf((char*)Message, \"%X, \", tmp);\n\t\t\t HAL_UART_Transmit(&huart2, Message, MessageLen, 100);\n\t\t }\n\n\t\t MessageLen = sprintf((char*)Message, \"\\n\\rWait for Tamper\\n\\r\\n\\r\");\n\t\t HAL_UART_Transmit(&huart2, Message, MessageLen, 100);\n\n\t\t RTC_TamperSet();\n\t\t TamperFlag = 0;\n\t }\n\n\t if(GPIO_PIN_RESET == HAL_GPIO_ReadPin(TEST_GPIO_Port, TEST_Pin))\n\t {\n\t\t while(GPIO_PIN_RESET == HAL_GPIO_ReadPin(TEST_GPIO_Port, TEST_Pin))\n\t\t {}\n\t\t SetRTC();\n\t }\n \/* USER CODE END WHILE *\/\n\n \/* USER CODE BEGIN 3 *\/\n }<\/pre>\n\n\n\n![\"\"](\"http:\/\/msalamon.pl\/wp-content\/uploads\/2020\/03\/rtcf4_tamper.png\")
<\/figure>\n<\/div>\n\n\nTamper + Time Stamp in STM32F4<\/h2>\n\n\n\n
![\"\"](\"http:\/\/msalamon.pl\/wp-content\/uploads\/2020\/03\/rtcf4_tamper_timestamp.png\")
<\/figure>\n<\/div>\n\n\n![\"\"](\"http:\/\/msalamon.pl\/wp-content\/uploads\/2020\/07\/Nucleo-64-baner.jpg\")
<\/a><\/figure><\/h2>\n\n\n\nSummary<\/h2>\n\n\n\n