| commit | 0a5e253da907d70ec0d5ad66b796d5019204f993 | [log] [tgz] |
|---|---|---|
| author | irodrig <ivan.rodriguez@bsc.es> | Mon Jun 14 18:18:56 2021 +0200 |
| committer | irodrig <ivan.rodriguez@bsc.es> | Mon Jun 14 18:18:56 2021 +0200 |
| tree | 90b799a37f69ec44abde712ea34bfe99c4080c10 | |
| parent | bd74133c5231e65a0b334a3da579ba83da065d87 [diff] |
documentation update
Version 2.0V Extended:
Version 2.0V:
Version 1.5V:
Version 1.4V:
Version 1.3V:
Version 1.2V:
Version 1.1V:
Version 1.0V:
The main goal of this project is to design open source radiation harden techniques. For now the space industry is a very close source and restricted IP industry. But from ESA and his partners there is increasing interest in open source software and hardware for space use. So the main goal of the project is to implement some radiation harden features and test them under radiation to see how this techniques behave. Due to the nature of this project that is using a node that is close to the nodes use in this industry we will be easy to compare to current solutions.
In detail this project aims to test different techniques for error detection and correction in registers. In this case is implemented a 32 bit register file that we be use at the same time (with some limitations) with the different techniques selected. This techniques are:
ECC: ECC with 1 bit correction and 2 bit correction
Triple Redundancy: The input value is triplicated in the register file
Shadow Register: The input value has a copy in the register file
ECC Shadow Register: The input value has a copy in the register file with ECC protection of 1 bit correction and 2 bit correction.
This is a full example of how to use the chip in the context of caravel. For this example we will write a value to the register 1 and then we will read that value from the register file. This is also the first test of the chip.
void main() { /* Set up the housekeeping SPI to be connected internally so */ /* that external pin changes don't affect it. */ reg_spimaster_config = 0xa002; // Enable, prescaler = 2, // connect to housekeeping SPI reg_mprj_io_31 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_30 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_29 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_28 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_27 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_26 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_25 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_24 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_23 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_22 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_21 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_20 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_19 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_18 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_17 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_16 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_15 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_14 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_13 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_12 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_11 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_10 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_9 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_8 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_7 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_5 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_4 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_3 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_2 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_1 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_0 = GPIO_MODE_USER_STD_OUTPUT; reg_mprj_io_6 = GPIO_MODE_MGMT_STD_OUTPUT; // Set UART clock to 64 kbaud (enable before I/O configuration) reg_uart_clkdiv = 625; reg_uart_enable = 1; /* Apply configuration */ reg_mprj_xfer = 1; while (reg_mprj_xfer == 1); // Configure LA probes // outputs from the cpu are inputs for my project denoted for been 0 // inputs to the cpu are outpus for my project denoted for been 1 reg_la0_oenb = reg_la0_iena = 0x00000000; // [31:0] reg_la1_oenb = reg_la1_iena = 0x00000000; // [63:32] reg_la2_oenb = reg_la2_iena = 0xFFFFFFFC; // [95:64] reg_la3_oenb = reg_la3_iena = 0xFFFFFFFF; // [127:96] // Flag start of the test reg_mprj_datal = 0xAB400000; // test code // clk and reset reg_la2_data = 0x00000001; reg_la2_data = 0x00000000; // add data to register 1 reg_la0_data = (1 << 2| 2 & 0x3); reg_la1_data = 200; // clk reg_la2_data = 0x00000001; reg_la2_data = 0x00000000; // read value to register 1 reg_la0_data = (1 << 2| 1 & 0x3); // clk reg_la2_data = 0x00000001; reg_la2_data = 0x00000000; // value is the GPIO [35:20] reg_mprj_datal = 0xAB410000; print("\n"); print("Monitor: Test 1 Passed\n\n"); reg_mprj_datal = 0xAB510000; }
For the of the code we use Hamming code for the implementation or the parity bits and correction. In this particularly case is implemented with 6 bits inside of the register (positions 1,2,4,8,16,32) and a extra bit at the last position of the 2 bit error detection.
The triple redundancy is implemented using the same registers that are been use for the ECC memory. The main issue of using this is the reduction in the space available for registers. But triple redundancy and standard ECC register can be use at the same time. Maintaining the consistency and witch registers are use and is witch mode each register is bee use is a job of the user.
In the chip can be at maximum of 8 triple redundancy registers and 8 ECC registers can be use at the same time.
The registers that can be use for triple redundancy are:
When one of this triple redundancy only a set of registers for ECC can be use. The registers that can be use when one of triple redundancy is use is:
The shadow register is implemented by only using the first 4 bits of register address for accessing the first 16 registers for store operations. The last bit of the address is use internally to store the value in a second register. So for example you store a value in the register 0 the shadow copy will be stored in the register 16. For this method only error detection is possible.
The ECC shadow register is implemented in a similar way of the shadow register but the values are store with the parity bits. In this case first the value is compare with the shadow register and second the not shadowed register is send to the parity verification to check the ECC value is correct, the output will be if the values has been corrected and/or was a mismatch between the values.
For this mode the data value is store with out any protection in the register file.
The main code part is in the ecc_registers folder inside of the rtl folder. The user_proj.v contains only the connections to connect the project wrapper with the register file. The module works in a black box manner, the values are inserted to the module and you can ask for a value inside of the memory and the output is the value requested with a status signal that tells if the value is correct without modifications, the value has been corrected or if the value data is invalid. Is important to notice that if more that two bits are flip in the register value the system can not reliable determine if the value is incorrect.
The module is implemented with 32 bit word size and 32 registers. The counters are 32 bit counters.
clk_i: Clock signal for the module.
rst_i: Reset signal for the module, this signal clears all of the values for the internal register values and all of the counters.
data_to_register_i [31:0]: The 32 bit input value that will be store in the register file.
register_i [2:0]: Signal to select the register that the operation will be perform.
wregister_i: Signal to indicate that the operation that you want is to write the input data to a register.
rregister_i: Signal to indicate that the operation that you want is to read from the register file.
operation_type_i [3:0]:This is a three bit signal that indicates what type of operation will apply to the data. This is use in conjunction with the wregister_i and rregister_i for writing and reading. The possible values are:
store_data_o [31:0]: The 32 bit value that was store in the register file
operation_result_o [1:0]. This is a two bit output that indicates the sate of the data.
operational_o. Signal that indicates if the system is ready to accept petitions for reading or writing.
Also some extra ports can be use in the case to add connection to a wishbone bus. For the current version the wishbone is only connected to the 32 bit counter that counts the number of 1 bit flip that have happened.
The module is connected to the caravel project so in this section we will define how is connected to the processor in order to interact with it.
Caravel offers multiple way to interact with the user project inside of it. This ways are GPIO ports, logic analyzer probes, and the Wishbone interconnection, user maskable interrupt signals.
Input probes:
Output probes:
The wishbone connection is 1 to 1 with the user project wrapper.
This signals are not connected.
The ecc registers module is compose of a set of multiple sub-modules. The following image is a representation of the modules and how each one of them interconnect.
In this chip is implemented the wishbone to access the 32 bit counters and also to access the internal registers in order to modify the first 32 bits for testing of the ECC capabilities.
The chip have to modes, operation mode where it performs the register file operations or in wishbone operation. The both modes are independent and can not be operated at the same time.
Each of the possible accesses of the wishbone has a predefined address to access. Following the design of caravel the first address is the 0x3000_0000. All of the possible address that are defined are configure to be read from or write to the wishbone interface. Regarding the PMU, now that you can access a counter per each of the registers. So the base address of the PMU points to the reads form the register 0, the following address point to writes, corrected errors, uncorrected errors. So each set of counters are separate by 4 address. so hereinafter this is the list of implemented addresses for the chip.
This example is base in that this chip is connected to the caravel project. The main idea of the use of the wishbone interface is that you are performing operations and then you stop doing operations and you change the chip to wishbone access. In the following example I will show how to access the performance counter that counts the number of reads.
First we define the address that will be use for the access of counter in this case is the reads so we use the address 0x30000004.
#define reg_wb_counter (*(volatile unint32_t*)0x30000004)
Second we operate the chip in a normal condition adding a value toa register and reading for it.
//############################################## //# Caravel GPIO configurations //############################################## //############################################## // la probes configurations //############################################## // clk and reset reg_la2_data = 0x00000001; reg_la2_data = 0x00000000; // add data to register 1 reg_la0_data = (1 << 2| 2 & 0x3); reg_la1_data = 200; // clk reg_la2_data = 0x00000001; reg_la2_data = 0x00000000; // read value to register 1 reg_la0_data = (1 << 2| 1 & 0x3); // clk reg_la2_data = 0x00000001; reg_la2_data = 0x00000000; // value is the GPIO [35:20]
When we want to access the performance counter we start the switching to wishbone mode. First to tell the chip to stop operating this is achieve putting the rregister_i and wregister_i to 0.
// clk reg_la2_data = 0x00000001; reg_la2_data = 0x00000000; // clear lines reg_la0_data = 0x00000000; reg_la1_data = 0x00000000; // clk reg_la2_data = 0x00000001; reg_la2_data = 0x00000000;
Then we need to deactivate the manual clock to switch the the wishbone clock. We doing that by deactivating the LA probes that access the clk and reset.
// deactivate internal clk reg_la2_oenb = 0xFFFFFFF;
Now we can check the value accessing to the defined variable.
// deactivate internal clk print (reg_wb_counter);
Now is the full example code
#define reg_wb_counter (*(volatile unint32_t*)0x30000000) void main() { //############################################## //# Caravel GPIO configurations //############################################## //############################################## // la probes configurations //############################################## // clk and reset reg_la2_data = 0x00000001; reg_la2_data = 0x00000000; // add data to register 1 reg_la0_data = (1 << 2| 2 & 0x3); reg_la1_data = 200; // clk reg_la2_data = 0x00000001; reg_la2_data = 0x00000000; // read value to register 1 reg_la0_data = (1 << 2| 1 & 0x3); // clk reg_la2_data = 0x00000001; reg_la2_data = 0x00000000; // value is the GPIO [35:20] // clk reg_la2_data = 0x00000001; reg_la2_data = 0x00000000; // clear lines reg_la0_data = 0x00000000; reg_la1_data = 0x00000000; // clk reg_la2_data = 0x00000001; reg_la2_data = 0x00000000; // deactivate internal clk reg_la2_oenb = 0xFFFFFFF; print (reg_wb_counter); }
For this project there is a set of test in order to verify the functionality described. The test are the following.
la_test1: This test is the basic test, write a value with ECC to a register and then reads that value from the memory.
la_test2: This test, writes and reads all of the 32 registers of chip using ECC.
la_test3: This test, writes and reads from one of the triple redundancy registers.
la_test4: This test, writes in a triple redundant register and modify two of the copies of the data stored to test that the error state is detected.
la_test5: This test writes and reads from one of the shadow registers.
la_test6: This test, writes and reads all of the 16 registers using shadow registers.
la_test7: This test, writes in a register using a shadow register and modify the shadow register to verify that the error is detected.
la_test8: This test writes and reads from one of the ECC shadow registers.
la_test9: This test, writes and reads all of the 16 registers using ECC shadow registers.
la_test10: This test, writes in a register using a ECC shadow register and modify the shadow register to verify that the error is detected.
la_test11: This test writes and reads from one register without using any protection.
wb_test1: This test uses the wishbone interface to modify one bit of an internal register in order to test the ECC functionality.
wb_test2: This test uses the wishbone interface to modify one bit of an internal register and also makes some reads in oder to check the performance counters.
wb_test3: This test uses the wishbone interface to modify one value of an internal triple redundant register and also makes a red to check that the output value is correct and the corrected stage is detected.
wb_test4: This test uses the wishbone interface to add a value per each of the 32 registers and then using the chip we read the 32 values. This is for testing the proper access of all of the registers.
wb_test5: This test is similar to the wb_test2 but verifies that the PMU-1 and PMU-2 have the same values for the total reads and corrected errors.
wb_test6. Using the base of the wb_test2 this test try's to access a non valid address the expected result is that the program finish without problems and without halting the processors.
wb_test7. Using as a base the la_test2, we write to all of the registers and we read all of them and we check some of the individual counters to check that the number of reads correctly as well the total reads and writes form the PMU-1 and PMU-2.