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Sitara Processors Forum
AM3359 Profibus support Questions
With respect to ProfiBus support in general and on the EVM:
#1) The ICE design is using UART1 (D15, D16) as the ProfiBus handler. Which I believe is then PR1_UART0 correct (the PRU unit's hardwired UART)? #2) So that means it needs to be set aside as the ProfiBus pins correct? #3) With that GPIO3_19 (C13) is being used in part of the ProfiBus control. Am I correct in assuming that this is something that would be locked in the PRU stack as well? So I need to assume it for ProfiBus?#4) Since the ProfiBus is still being worked on its hard to look at what is going on - from what I can tell the code/stack piece items would be available by end of Q1 2012 correct? And given that any idea as to if a cost would be associated with it?
1. Yes, UART inside the PRU subsystem is used for PROFIBUS.
3. Likely yes. We will confirm.
4. It is coming in the industrial SDK release due in 4-5 weeks from now. These are available as part of the AM1810 SDK already and will get tested for AM335x ICE as well by the time of release. There is no cost to develop and use PROFIBUS. When you want to move your product into production, a license from PROFIBUS stack vendor is required.
In addition to Maneesh reply, here are the pins used for Profibus.
For ZCZ package:
Pin signal in mode 0 mode5 (used) profibus control signals
C13 MCASP0_FSR_MUX0 PR1_PRU0_PRU_R30 TX_ENABLE
D16 UART1_RXD PR1_UART0_RXD_MUX1 UART1_RXD
D15 UART1_TXD PR1_UART0_TXD_MUX1 UART1_TXD
So in nutshell, we are using the above mentioned pins in mode 5 for profibus control signals.
So that means Profibus has to be used only with this pins? (D16,D15)
Is it not implementable in other UARTs or muxed with other pins?
The PROFIBUS code must be run in a PRU: it cannot run in a standard UART, etc. because the PRU is essentially replacing the SPC3 ASIC (for example) that is normally used on a PROFIBUS slave device.
PRU-ICSS UART RX/TX signals (PR1_UART0_RXD/TXD) used for PROFIBUS implementation are available on following pins as well
B16 SPI0_D1 MODE4
A16 SPI0_CS0 MODE4
My question is regarding the PRU where the Profibus FDL code is used. I underatood that the Profibus DpV0 DPV1 layer7 Application code is run on the Sitara microcontroller where all the other application code is also running then why isn't the Profibus FDL micro code(Layer 1) is run in PRU subsystem. Why the Cortex controller cannot handle the micro code as well ?
PROFIBUS DP v0/v1 slave firmware for PRU was originally developed on AM18xx (ARM9 @ 312MHz) and it made sense to FDL layer processing in PRU which guarantees deterministic real time then to support higher baud rates (12 Mbaud)
AM335x s/w architecture is a full reuse from AM18xx which is certified by PNO.
What is the actual concern here?
Actually I am looking for only the Profibus FDL micro code stack.That is the datalink layer firmware of profibus which means in your case it is the micro code running on PRU subsystem. My major concern is I have the application microcontroller which would be running all the Application layer services as well as the datalink layer microcode. The microcontroller has a single core CPU which would be bearing the load of some applcations as well as the entire layer of profibus. I want to purchase only the datalink layer firmware of profibus which means in your case it is the micro code running on PRU subsystem. My question is that how much would be the speed of execution required by my microcontroller CPU core additionally to execute the datalink layer firmware of Profibus? This question came in my mind because AM18xx which is certified by PNO has one ARM core and also a special PRU for processing the Micro code.
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