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> Arm CPUs are not better. To make a hardware design with MediaTek Genio 1200 (quadruple Cortex-A78) or Rockwell RK3588 (quadruple Cortex-A76), you still need t

by bpye 2y ago

> Arm CPUs are not better. To make a hardware design with MediaTek Genio 1200 (quadruple Cortex-A78) or Rockwell RK3588 (quadruple Cortex-A76), you still need to get under NDA the required documentation. Only for microcontrollers like those made by Renesas, Infineon, ST, NXP, Microchip etc. you may find the complete documentation on-line. Perhaps less interesting, but there are a handful of Cortex-A SoCs from TI [0] and NXP [1, 2], at least, that have non-NDA datasheets and reference manuals. [0] - https://www.ti.com/microcontrollers-mcus-processors/arm-based-processors/overview.html https://www.ti.com/microcontrollers-mcus-processors/arm-base... [1] - https://www.nxp.com/products/processors-and-microcontrollers/arm-processors/i-mx-applications-processors:IMX_HOME https://www.nxp.com/products/processors-and-microcontrollers... [2] - https://www.nxp.com/products/processors-and-microcontrollers/arm-processors/layerscape-processors:QORIQ-ARM https://www.nxp.com/products/processors-and-microcontrollers...

adrian_b 2y ago
True, but all those are really obsolete Cortex-A cores. The Cortex-M cores used in microcontrollers have a much slower evolution, but the Cortex-A cores are updated every year and the differences between the more recent cores and the older cores are very big. Cortex-A78, like in MediaTek Genio 1200 is the 2021 Cortex-A core. Cortex-A76, like in RK3588 and Raspberry Pi 5 is the 2019 Cortex-A core, already 5 years old. All older Cortex-A cores are hopelessly obsolete. There still are some borderline acceptable SBCs that use Cortex-A73, the 2017 Cortex-A core, i.e. 7 years old. The NXP and TI products use much weaker Cortex-A cores than even that. The only NXP products with Cortex-A cores that can be acceptable for certain purposes are those with Cortex-A55 cores (2018). These at least support the Armv8.2-A ISA, which corrects some important defects in the original Armv8-A instruction set. Nevertheless, the Cortex-A55 cores are very small and slow, so using a CPU with them is justified only if that results in a much smaller or much cheaper SBC than when using Cortex-A7x cores. That means that any acceptable SBC that uses Cortex-A55 cores must be small and fanless, e.g. a fanless credit-card-sized SBC that must be cheap too, e.g. not exceeding $50 unless it contains a lot of memory and interfaces that could justify a price slightly higher than that. Many of the solutions using TI or NXP Cortex-A based devices fail to satisfy the power consumption, size and price values that are expected for such cores (frequently due to their use of ancient manufacturing processes, which may make a Cortex-A55 consume as much power as a Cortex-A7x made with a newer CMOS process). NXP makes microcontrollers with 1 GHz Cortex-M7 cores, which are good enough for many of the applications for which Raspberry Pi SBCs have been used. For the remaining applications, which need fast interfaces, like for SSDs, USB 3 or multiple Ethernet interfaces, it is better to go directly to a SBC like Radxa X4, so there are only very few applications where a device with obsolete Cortex-A cores can be preferred to a either a cheaper microcontroller or a faster Intel Atom CPU.

by bpye 2y ago

adrian_b 2y ago

True, but all those are really obsolete Cortex-A cores. The Cortex-M cores used in microcontrollers have a much slower evolution, but the Cortex-A cores are updated every year and the differences between the more recent cores and the older cores are very big. Cortex-A78, like in MediaTek Genio 1200 is the 2021 Cortex-A core. Cortex-A76, like in RK3588 and Raspberry Pi 5 is the 2019 Cortex-A core, already 5 years old. All older Cortex-A cores are hopelessly obsolete. There still are some borderline acceptable SBCs that use Cortex-A73, the 2017 Cortex-A core, i.e. 7 years old. The NXP and TI products use much weaker Cortex-A cores than even that. The only NXP products with Cortex-A cores that can be acceptable for certain purposes are those with Cortex-A55 cores (2018). These at least support the Armv8.2-A ISA, which corrects some important defects in the original Armv8-A instruction set. Nevertheless, the Cortex-A55 cores are very small and slow, so using a CPU with them is justified only if that results in a much smaller or much cheaper SBC than when using Cortex-A7x cores. That means that any acceptable SBC that uses Cortex-A55 cores must be small and fanless, e.g. a fanless credit-card-sized SBC that must be cheap too, e.g. not exceeding $50 unless it contains a lot of memory and interfaces that could justify a price slightly higher than that. Many of the solutions using TI or NXP Cortex-A based devices fail to satisfy the power consumption, size and price values that are expected for such cores (frequently due to their use of ancient manufacturing processes, which may make a Cortex-A55 consume as much power as a Cortex-A7x made with a newer CMOS process). NXP makes microcontrollers with 1 GHz Cortex-M7 cores, which are good enough for many of the applications for which Raspberry Pi SBCs have been used. For the remaining applications, which need fast interfaces, like for SSDs, USB 3 or multiple Ethernet interfaces, it is better to go directly to a SBC like Radxa X4, so there are only very few applications where a device with obsolete Cortex-A cores can be preferred to a either a cheaper microcontroller or a faster Intel Atom CPU.