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195 lines
8.0 KiB
Markdown
195 lines
8.0 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/FRAM_I2C/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/FRAM_I2C/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/FRAM_I2C/blob/master/LICENSE)
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[](https://github.com/RobTillaart/FRAM_I2C/releases)
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# FRAM_I2C
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Arduino library for I2C FRAM.
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## Description
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FRAM is a library to read from and write to (over I2C) an FRAM module.
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The library has (since 0.4.0) two classes **FRAM** and **FRAM32**.
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The first is for the 16 bit devices and the latter for the 32 bit devices.
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Currently only the **MB85RC1MT** is known to be 32 bit.
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**FRAM32** can also address 16 bit devices although there is some overhead in footprint.
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FRAM stands for Ferroelectric RAM - https://en.wikipedia.org/wiki/Ferroelectric_RAM
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FRAM memory is much faster than EEPROM and almost as fast as (Arduino UNO) RAM.
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Another important feature FRAM has in common with EEPROM is that FRAM keeps
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its content after a reboot as it is non-volatile, even for years.
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That makes it ideal to store configuration or logging data in a project.
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Types of FRAM that should work with this library:
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| TYPE | SIZE | TESTED | NOTES |
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|:----------:|-------:|:------:|:---------------------|
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| MB85RC04 | 512 | | no deviceID register |
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| MB85RC16 | 2 KB | | no deviceID register |
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| MB85RC64T | 8 KB | Y | |
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| MB85RC128A | 16 KB | | no deviceID register |
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| MB85RC256V | 32 KB | Y | |
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| MB85RC512T | 64 KB | Y | |
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| MB85RC1MT | 128 KB | Y | since 0.4.0 FRAM32 only |
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#### Notes
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- Not all types of FRAM are tested. Please let me know if you have verified one that is not in the list.
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- If there is no deviceID **getSize()** will not work correctly.
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- Address = 0x50 (default) .. 0x57, depends on the lines A0..A2.
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- **MB85RC1MT** uses even addresses only as it uses the next odd one internally. So 0x50 uses 0x51 internally for the upper 64 KB block.
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This latter will not be shown on an I2C scanner (to be tested).
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## Interface
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### Constructor
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- **FRAM(TwoWire \*wire = &Wire)** Constructor with optional Wire interface.
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- **FRAM32(TwoWire \*wire = &Wire)** Constructor with optional Wire interface, specific for **MB85RC1MT** type of device.
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- **int begin(uint8_t address = 0x50, int8_t writeProtectPin = -1)** address and writeProtectPin is optional.
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Note the **MB85RC1MT** only uses even addresses.
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- **int begin(uint8_t sda, uint8_t scl, uint8_t address = 0x50, int8_t writeProtectPin = -1)** idem for ESP32 a.o.
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- **bool isConnected()** checks if the address is visible on the I2C bus.
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### Write & read
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Support for basic types and 2 calls for generic object, use casting if needed. In the **FRAM32** class these functions have an **uin32_t memaddr**.
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- **void write8(uint16_t memaddr, uint8_t value)** uint8_t
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- **void write16(uint16_t memaddr, uint16_t value)** uint16_t
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- **void write32(uint16_t memaddr, uint32_t value)** uint32_t
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- **void write(uint16_t memaddr, uint8_t \* obj, uint16_t size)** other types / sizes.
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- **uint8_t read8(uint16_t memaddr)**
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- **uint16_t read16(uint16_t memaddr)**
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- **uint32_t read32(uint16_t memaddr)**
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- **void read(uint16_t memaddr, uint8_t uint8_t \* obj, uint16_t size)**
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One needs to allocate memory as the function won't.
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(0.3.4 added template functions, see issue #13 )
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- **uint16_t writeObject(uint16_t memaddr, T &obj)** writes an object to memaddr (and following bytes).
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Returns memaddr + sizeof(obj) to get the next address to write to.
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- **uint16_t readObject(uint16_t memaddr, T &obj)** reads an object from memaddr and next bytes.
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Returns memaddr + sizeof(obj) to get the next address to read from.
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(0.3.5 added)
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- **uint32_t clear(uint8_t value = 0)** clears the whole FRAM by writing value to all addresses - default zero's.
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Returns the number of bytes written..
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### Miscellaneous
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- **bool setWriteProtect(bool b)** make the FRAM write-protected by pulling line HIGH / LOW.
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Returns true if a writeProtectPin was defined.
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Otherwise the FRAM cannot be write protected.
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Note the pin should be defined in **begin()**.
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- **bool getWriteProtect()** get current write protect status.
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- **uint16_t getManufacturerID()** idem. Fujitsu = 0x00A.
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- **uint16_t getProductID()** idem. Proprietary.
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- **uint16_t getSize()** returns size in kiloBYTE.
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If the FRAM has no device ID, the size cannot be read.
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- **uint32_t getSizeBytes()** returns size in BYTES.
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Convenience wrapper, useful for iterating over the whole memory,
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or testing the upper boundary.
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- **void setSizeBytes(uint32_t value)** sets size in bytes for **getSizeBytes()**.
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To be used only if **getSize()** cannot determine the size.
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See also remark in Future section below.
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### Sleep
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(0.3.6 added - experimental)
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- **void sleep()** puts the FRAM in sleep mode so it uses less power.
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Still needs a power test for 2 types of FRAM.
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- **bool wakeup(uint32_t trec = 400)** tries to wake up the device with a default recovery time of 400 microseconds.
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Returns true if connected after the call.
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According to the data sheets there are only three FRAM devices support the sleep command.
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So use with care.
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| TYPE | SIZE | SLEEP (datasheet)| CURRENT | CONFIRMED | NOTES |
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|:----------:|-------:|:----------------:|:---------:|:---------:|:--------|
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| MB85RC04 | 512 | not supported | - | N | |
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| MB85RC16 | 2 KB | not supported | - | N | |
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| MB85RC64T | 8 KB | Y Page 11 | 4.0 uA* | N | |
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| MB85RC128A | 16 KB | not supported | - | N | |
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| MB85RC256V | 32 KB | not supported | - | Y | |
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| MB85RC512T | 64 KB | Y Page 12 | 4.0 uA* | N | |
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| MB85RC1MT | 128 KB | Y Page 12 | 3.6 uA | Y | See #17 |
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_current with \* are from datasheet_
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### Current
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Indicative power usage in uA in three modi (if supported).
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| TYPE | SIZE | STANDBY | WRITE | SLEEP | NOTES |
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|:----------:|-------:|:--------:|:---------:|:---------:|:--------|
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| MB85RC04 | 512 | | | - | |
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| MB85RC16 | 2 KB | | | - | |
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| MB85RC64T | 8 KB | | | 4.0 uA | |
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| MB85RC128A | 16 KB | | | - | |
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| MB85RC256V | 32 KB | 10.22 uA | 93.48 uA | - | |
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| MB85RC512T | 64 KB | | | 4.0 uA | |
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| MB85RC1MT | 128 KB | 11.7 uA | 46-721 uA | 3.6 uA | See #17 |
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_TODO: fill the table_
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## Operational
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See examples
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## Future
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### high
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- improve **FRAM32** that can write over the 64 KB border without problems.
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- Would cause extra checking ==> overhead.
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- now it is responsibility user.
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- do we want/need this?
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### medium
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- **write()** and **writeBlock()** might write beyond the end of FRAM
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- now it is responsibility user.
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- testing would degrade performance?
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- error flag ?
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- extend examples
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- FRAM for multi language string storage
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- FRAM as linear buffer for a slow stream?
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- FRAM as ring buffer
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- FRAM logging, unequal length strings.
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- FRAM (8x) concatenated as one continuous memory.
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### low
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- test more types of FRAM
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- **getSize()** scanning FRAM like EEPROM library?
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- remember last written address? why?
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- fill power usage table
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### wont
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- extend current **clear()** with partial **clear(begin, end, value)**?
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- can be done by **writeBlock()** calls by user too
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- would need more complex end checking
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- ==> wont for now
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- **dump(stream)** or printable interface?
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- Print interface? expensive in performance per char..
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